List of recurring Earth characters in Stargate SG-1
Stargate Command personnel 
The Stargate Command (SGC) is a fictional military base at the (real) Cheyenne Mountain complex near Colorado Springs, Colorado. It is the main setting in Stargate SG-1 and occasionally features on Stargate Atlantis. The base extends many levels beneath the ground and is protected from most forms of attack including indirect nuclear detonations, also serving to contain biological, chemical or alien hazards to the outside world by means of a 'lockdown' status. Stargate Command is typically commanded by a General and is staffed by subject matter experts and military support personnel, several elite special operations teams, and several SG teams, including SG-1. The majority of the teams are United States Air Force with some United States Marine Corps, civilians and United States Army, but other nations have SG teams operating from the SGC as well after the events of season 5.
Kevin Elliot 
Lieutenant Kevin Elliot, (played by Courtenay J. Stevens, season 5) – See Martouf – Is transferred to SG-17 after successfully proving his worth in an elaborative test for SGC recruits. All of SG-17 was killed on his first day of off-world duty, except for Elliot, in an attack on the underground Tok'ra by the Goa'uld. Elliot was saved only because of the implantation of the Tok'ra symbiote Lantash. Lantash and Elliot give their lives to save the rest of the team when they realize that Lantash did not have the strength to repair Elliot's injuries and save their lives. Elliot/Lantash were given a vial of Symbiote poison, powerful enough to eliminate the entire occupied force, and, presumably, used it on them to allow SG-1 and Jacob Carter to escape.
According to portraying actor Courtenay J. Stevens, the first draft for the character was that he was supposed to be a young Jack O'Neill in the then new-spin off show Stargate Atlantis. The producers dropped Elliot and minimized his role so that he was never even mentioned in Stargate Atlantis. Many fans of Stargate thought that Elliot and his team would replace Samantha Carter, Teal'c, Daniel Jackson and O'Neill as the main characters of the show. Stevens has stated that the producers took much time to look at new "Options", for the series and further stated that he knew "they were looking at it". But the plans were changed and actor Stevens left the Stargate set in Vancouver after the shooting of "Last Stand".
When shooting the episode, "Summit" J.R. Bourne was booked, so he was replaced with Stevens. Before being cast in the episode "Summit", the producers told the history behind the Tok'ra symbiote Lantash. Stevens was later cast as Keras in the Stargate Atlantis episode "Childhood's End".
Janet Fraiser 
Captain Janet Fraiser, the resident Chief Medical Officer of the SGC. (played by Teryl Rothery, seasons 1–7, 9) – She is responsible for maintaining the health of the SG teams, as well as the SGC's support staff and base personnel. On many occasions, she also cares for the health of alien refugees to Earth, including Goa'uld symbiotes. In her first appearance in "The Broca Divide", Dr. Fraiser holds the rank of Captain, and is promoted to Major in Season 3. In season 1's "Singularity", Fraiser adopts Cassandra, an alien orphan whose people had been exterminated by the Goa'uld System Lord Nirrti. Dr. Fraiser is killed by a staffweapon blast in season 7's "Heroes" during an off-world medical emergency, but she returns in season 9's "Ripple Effect" as a parallel universe version of Dr. Fraiser, in her reality a regular member of SG-1. Before Fraiser returns to her reality, Carter, Jackson and Teal'c are able to give her a final goodbye. Dr. Fraiser is also shown alive in an alternate timeline in the year 2010 in season 4's "2010", but Fraiser and SG-1 alter the timeline to prevent a catastrophe on Earth involving the Aschen race.
Fraiser joined the United States Air Force (USAF) after breaking up with her husband; there she got some training with firearms. Her husband didn't want Fraiser to join the US military which is one of the main reasons for their breakup. As a doctor, Fraiser looks for peaceful solutions and is disinclined towards armed solutions. In the episode "Serpent's Song", Fraiser is the only one in Stargate Command (SGC) who is resistant to the idea to give Apophis over to his enemies. She is eventually forced to give up Apophis.
Teryl Rothery was asked by then producer and writer (for Stargate) Jonathan Glassner and Brad Wright if she wanted to play the role as Fraiser. In an interview, Rothery was asked what it was like to play a doctor in Stargate SG-1. Rothery replied, "just being true to the character. And as far as the medical stuff, knowing what to do and what to say." She got a lot of help from the medical advisor on the set.
In the first two seasons, Rothery didn't have a contract and was booked on every episode in which she appeared. In season three of SG-1, she finally got a contract deal with the producers. She also commented on her acting life once:
|“||"The life of an actor is always very up and down. So sometimes you work a lot, but sometimes ... So if you're on a series like Stargate SG-1 you have that work for seven years. So that's a gift."||”|
After her character's death in season 7, there were various rumours which said she would appear in the upcoming Stargate film; this never happened. Rothery said it was unlikely since she hadn't had any contact with the Stargate producers since her character's death. Rothery has stated many times that she "admires" the character because of her "strength" and "intelligence". Robert C. Cooper, producer for Stargate SG-1, called Rothery about the death of her character. Cooper said, "It is our last year, so we are thinking of killing one of our regulars." Fraiser was killed off in the episode "Heroes" because the producers thought season seven would be the last in the series and felt that a death of the main cast was needed. Rothery also appeared on the Women of Sci-Fi calendar produced by fellow Stargate cast Michael Shanks and Christopher Judge.
Walter Harriman 
Chief Master Sergeant Walter Harriman (also known as the Chevron Guy among others, portrayed by Gary Jones, seasons 1–10) is a fictional character in the Canadian-American television series Stargate SG-1, who joined the Stargate Command (SGC) after excelling in navigation and automatic flight control operations during the first Gulf War. General Hammond recruited him as someone with excellent technical ability and a cool head to operate the Stargate under extreme pressure. He specializes in installing, maintaining and repairing bomb navigation, weapons control as well as automatic flight control systems. He is also an expert in radio and navigational equipment, and in maintaining test and precision measurement equipment. He is primarily a Stargate technician, running the dialing computer and other equipment from the Control Room. He also acts as an occasional administrative assistant to the head of Stargate Command, and has manned the flight console on the bridge of the Prometheus. From season 8 to 10 Harriman's role is expanded to advisor to the Head of Command of the SGC
His name has been a source of confusion for many fans of Stargate SG-1. Originally, he was simply "Technician" or "Sergeant", listed as such in the show credits. At some point, some of the writers gave him the name "Norman Davis", which came with a name tag, but was never used in dialogue. In the episode "2010", Jack O'Neill refers to him as "Walter". Later, in the eighth season of "Stargate SG-1", the character is addressed as "Sergeant Harriman", resulting in the final name of "Walter Harriman". Many fans fondly refer to him as "the Chevron guy" as many of his on-screen appearances, especially earlier on in the show, had him saying "Chevron (insert number here) encoded". On several DVD commentaries after the introduction of the name "Walter", producer-director Peter DeLuise refers to the character as "Walter Norman" and "Walter Norman Davis". The first time he ever says his own name is in the Stargate Atlantis episode "Home".
As the series continued Harriman got a heavier role in the series. According to Jones, his role was expanded since Richard Dean Anderson wanted him as his personal assistant in the show when his character Jack O'Neill was the leader of the SGC. The Stargate producer and writer staff called 2005, The Year of Walter because the staff evolved Harriman's relationship with General Hank Landry. Jones does not have a binding contract with the Stargate producers.
Charles Kawalsky 
Major Charles Kawalsky portrayed by John Diehl (in the film) and Jay Acovone (in the series), was first introduced in the 1994 Stargate, as Jack O'Neill's second in command for the first mission through the stargate. In the film Kawalsky holds the rank of Lieutenant Colonel in the United States Air Force. He is recruited by General W.O. West to become a member of the first mission through the Stargate. On Abydos under the orders of O'Neill, he takes up the fight against Ra. Kawalsky's relationship with Daniel Jackson worsens throughout the film because Jackson is unable to return them to Earth. He changes his view of Jackson after they defeat Ra. He, O'Neill and Louis Ferretti decide to keep silent about what really happened during their mission to the planet.
When the Goa'uld Apophis attacks Stargate Command (SGC), Captain Kawalsky is reunited with his former teammates and questioned by General George Hammond. Both he and Feretti refuse to speak about the mission to Abydos. O'Neill is eventually forced to tell that Daniel Jackson is still alive, and O'Neill, Kawalsky and Ferretti are ordered to bring Jackson back to Earth. After what happened in the Stargate film, Kawalsky is promoted to major and becomes the leader of the newly formed SG-2, accompanying SG-1 on their mission to Chul'ac to rescue Sha're and Skaara. SG-2 guarded the Stargate and provided cover for SG-1 when they fled from the pursuing Jaffa. Before Kawalsky returns to Earth, he is invaded by a Goa'uld parasite from a dead Jaffa warrior.
Back on Earth the symbiote starts to take control of him, resulting in several blackouts. The medical staff of the SGC try to surgically remove the Goa'uld from his body. Though initially successful, the symbiote turns out to be a dead husk whose intelligence has already taken over Kawalsky's mind. He frees himself and tries to flee from the base, setting off a self-destruct mechanism as he dials the Stargate. He is apprehended by Teal'c while the self-destruct mechanism is disarmed. They fight in front of the open Stargate. Kawalsky is killed when Teal'c forces his head through the event horizon and closes the gate, severing most of Kawalsky's skull including the lobes controlled by the symbiote.
Kawalsky appears in three more episodes of the series in flashback. The first is "The Gamekeeper", in which O'Neill and Teal'c encounter Kawalsky in a virtual reality simulation. In "Point of View", Kawalsky and Samantha Carter from an alternate reality arrive through the gate seeking help in contacting the Asgard. His last appearance is in season 8, in which Kawalsky returns in an alternate timeline accidentally created when the destruction of their time machine traps SG-1 in the distant past. In a partial mirror to the pilot, Kawalsky accompanies O'Neill, Carter and Daniel to Chulak in part two of "Moebius". In this last appearance, he again meets his end, although here he is merely shot; it is the alternate Daniel Jackson who is infected with the Goa'uld and killed by Teal'c.
Darren Sumner called Kawalsky "one of the  film's strongest characters". Sumner called the high death numbers of secondary and recurring characters on the show, The Kawalsky Effect. A Kawalsky action figure was created after the release of the 1994 film. He also has a card in the card game, Stargate TCG. In the card game he is listed as a good soldier. While only appearing in six episodes in total, actor Jay Acovone frequently appears at Stargate conventions.
"Sly" Siler 
Master Sergeant "Sly" Siler, (played by Dan Shea, seasons 1–10) – A sergeant at the SGC and one of its primary technicians and engineers. First appearing in season 1's "Solitudes", he remains a background character throughout the run of Stargate SG-1 and also occasionally appears in Earth-based episodes of Stargate Atlantis. Dan Shea is primarily the stunt co-ordinator for Stargate SG-1, responsible for the budgets and locations of stunts, and the hiring of stunt people before co-ordinating all stunt action. He is also a stunt double for Richard Dean Anderson, for whom he stood in and stunt-doubled in MacGyver. Siler is subsequently shown to be involved in many accidents at the SGC, which is parodied in dialogue and action in several SG-1 episodes such as season 4's "Window of Opportunity", season 7's "Heroes" and the milestone episode "200".
Shea first auditioned for the role as Siler with executive producer Brad Wright and director Martin Wood. Shea commented on his first audition that he tried to be "Funny", thinking he could get the role easier that way. Executive producer Michael Greenberg said that Shea "Blew it", Shea then went for a second audition acting more serious, since according to Greenberg the role was "Serious" and he needed to act that way. Siler also frequently appears in the background of scenes carrying an oversized wrench, which he sometimes hands to director Martin Wood as a gag prop in the series. Siler's first name is never mentioned in dialogue in the series, although his uniform patch and magazines give his first name as "Sly" several times, and his uniform patch in "Entity" reads "Dan". According to producer and writer Peter DeLuise, Siler's name and dialog deliberately contain the letter "S" because Dan Shea lisps.
Shea had previous worked with both Richard Dean Anderson (who portrayed Jack O'Neill) and Greenberg before on the American television series MacGyver in the 80s and early 90s as Anderson's stand-in in stunt scenes, he continued this role in Stargate SG-1. Anderson's partner Greenberg gave the job as stunt coordinator and stand-in to Shea in Stargate SG-1. The first time Shea was officially double for Anderson was in Toronto when they did a MacGyver movie; Anderson had broken his foot so Shea was forced to do a stand-in.
Minor characters 
Major Louis Ferretti, (played by French Stewart in the film as Technical Sergeant Louis Ferretti and Brent Stait in season 1) – A member of the United States Air Force and one of the four survivors of the first expedition through the Stargate in Stargate. Ferretti joins O'Neill's team on another mission to Abydos in "Children of the Gods", and is put in charge of the SG-2 team after the death of Charles Kawalsky in "The Enemy Within". Ferretti makes his last appearance in "Within the Serpent's Grasp" to follow SG-1 through the Stargate, and is mentioned in season 3's "Shades of Grey" as a possible new leader of SG-1.
Colonel Robert Makepeace (played by Steve Makaj, seasons 1–3) was a former member of the United States Marine Corps and of Stargate Command (SGC). Originally, Makepeace was the commander of SG-3. His first on-screen appearance is in "The Broca Divide" as ranking officer and team leader of SG-3. He reappears in the two episodes, two-parters in Stargate SG-1 season 2. In the two-parters of season 2, Makepeace leads a rescue mission to save SG-1 (without Teal'c) from the grasp of Hathor in "Into the Fire". In season 3's "Shades of Grey", Makepeace is discovered to be a spy for the rogue N.I.D. group under the command of Colonel Harry Maybourne, who is covertly reverse-engineering stolen alien technologies. Smaller items stolen by the rogue group would be left on a designated world for Makepeace to covertly pick up and pack back to Earth in his gear during routine missions. O'Neill had Makepeace arrested and charged with high treason against the United States and its allies. While it is unknown who immediately replaced Makepeace as the commander of SG-3, eventually this position was assigned to Colonel Reynolds.
Colonel Albert Reynolds, (played by Eric Breker, seasons 2, 5, 7–10) – Introduced in "Touchstone" as a Major stationed at Area 51 and a member of the National Intelligence Department (NID).In early 2001, He is promoted to Lieutenant Colonel and was given command of SG-16 on a mission to Velona. Empty citation (help) By early 2003, Reynolds had received command of SG-3, succeeding Robert Makepeace who was charged for high treason against the United States and its allies. He was also one of the few airman who helped Jack O'Neill defend Stargate Command against the Replicator army that Replicator Carter had sent through the Stargate to attack Earth while she focused on conquering the Milky Way galaxy. Reynolds was the leader of the SGC during Hank Landry's vacation to Jack O'Neill's cabin, Samantha Carter assumed his post until he returned from his mission to P9J-333.
Doctor Robert Rothman, (played by Jason Schombing, seasons 3–4) – A scientist who prior to joining Stargate Command was Daniel's research assistant. He first appears in season 3's "Forever In A Day" in a Hand device-induced delusion of Daniel Jackson, where he is placed on SG-1. His first non-fantasy appearance is in "Crystal Skull", where Rothman is tasked with researching a crystal skull. Rothman becomes a host to a Goa'uld larva and during a rescue mission on an offworld archaeological dig site in "The First Ones" and is shot dead by Colonel Jack O'Neill.
Major Michael Griff, (played by Russell Ferrier, season 4) – Was a member of SG-2 as a captain. He accompanied SG-1 in its search to recover SG-11 and Dr. Daniel Jackson on P3X-888; during the course of the mission he was wounded by a staff weapon blast, but recovered. As commander of SG-2, Griff led a search for SG-1 after that team went missing on P3R-118. After braving a glacier that Administrator Calder had insisted SG-1 had set out to investigate, he became convinced that Colonel O'Neill would never have authorized such a mission. At General Hammond's instruction, Griff drew up plans for a covert search and rescue mission, which ultimately proved unnecessary. Later that year, Griff and SG-2 were assigned to "babysit" a team of scientists on M4C-862, a mission he sarcastically described as "non-stop excitement". When O'Neill and Teal'c arrived to relieve him, he was visibly pleased not to be responsible for dealing with the scientists anymore.
Doctor Bill Lee, (played by Bill Dow, seasons 4, 6–10) – A civilian scientist and engineer who works at Stargate Command and is often called upon to work with alien technology. He first appears in "Prodigy" but does not step in the foreground until "Evolution" where he and Daniel go on a mission to Honduras to locate the Ancients' healing device but are captured and tortured by local terrorists. As seen in "Heroes", Dr. Lee is responsible for creating a staff weapon-resistant armor. He is also a recurring character on Stargate Atlantis. He devises a way to relay a warning to Atlantis in "Critical Mass" and gates to the Pegasus Galaxy from the Midway Station in "Adrift" when Atlantis goes missing. Dr. Lee remains stationed at Midway, training Kavanagh as his replacement, until the midway station is destroyed in "Midway". Dr. Lee is seen in Stargate Universes pilot "Air" as the person Dr. Nicholas Rush (Robert Carlyle) transfers to using the Communication device with stones (see Ancient technology in Stargate)
Major Evan Lorne, (played by Kavan Smith, seasons 7 and 10) – A member of SG-11, Lorne first appears in Stargate SG-1 episode "Enemy Mine". Lorne appears as the team leader of the SG-1 unit in an alternate universe in the SG-1 season 10 episode "The Road Not Taken". Lorne reappears as a part of the new personnel sent after the Wraith siege by the Daedalus in Stargate Atlantis.
Doctor Carolyn Lam, (played by Lexa Doig, seasons 9–10) – Stargate Command's chief medical officer in seasons 9 and 10. She first appears in "Avalon Part 2" and is seemingly the first permanent one since the death of Dr. Janet Fraiser in season 7. Prior to joining Stargate Command, Dr. Lam worked with the Centers for Disease Control and Prevention; her specialty is infectious diseases. Dr. Lam has a strained relationship with her father, General Hank Landry. In "The Fourth Horseman", General Landry apologizes for not having been with her when she needed him as a child. Carolyn, her father and her mother Kim Lam, have dinner in the episode "Family Ties". Actress Lexa Doig is the real life spouse of Michael Shanks, who plays Daniel Jackson.
Secret intelligence characters 
The National Intelligence Department (NID) is a shadowy intelligence agency that appears throughout the run of Stargate SG-1 and occasionally on Stargate Atlantis. The official mandate of the NID is to provide vital civilian oversight of top secret military operations, but one of their unofficial primary goals is to procure alien technologies. A set of well-resourced illegal cells named the Rogue NID uses unscrupulous methods to achieve the goals of the official NID and is later replaced by The Trust, a shady interplanetary terrorist group. The International Oversight Advisory (IOA) is a civilian oversight committee created after the United States and Russia revealed the existence of the Stargate Program to the other permanent members of the UN Security Council in season 6.
Malcolm Barrett 
Special agent Malcolm Barrett, (played by Peter Flemming, seasons 5–7, 9–10) – An NID agent introduced in season 5's "Wormhole X-Treme!". His first significant appearance follows in "Smoke & Mirrors", where he helps uncovering a shadow group behind the NID who tried to attribute Senator Kinsey's apparent assassination to O'Neill. After collaborating with SG-1 in season 7's "Heroes, Part 2" and "Resurrection", Barrett expresses a personal romantic interest in Samantha Carter in season 9's "Ex Deus Machina" and season 10's "Uninvited", but she rejects his advances. His last SG-1 appearance is in "Dominion". Agent Barrett also recurs in Stargate Atlantis.
He warns General Landry in season 2's "Critical Mass" of the The Trust's plan to destroy Atlantis with a bomb, and aids several Expedition team members to track down Rodney McKay's sister Jeannie Miller on Earth in season 4's "Miller's Crossing".
Peter Flemming had a two-line audition for "Wormhole X-Treme" for a "Man in Black" character in a possible recurring role. Every NID character introduced before Agent Barrett "had been very shady, always had an agenda", and Barrett was "the first mainstay in NID who is actually law-abiding[...], honest, [and] a good person".
Colonel Chekov, (played by Garry Chalk, seasons 5–6, 8–10) – Russia's liaison to Stargate Command following the early season 4 events of the short-lived Russian Stargate program. He first appears in season 5's "The Tomb", blaming SG-1 for the death of several Russian SG team members. Chekov collaborates with the SGC several episodes later in "48 Hours", giving them a DHD from Russian possession and allowing the SGC to use the Russian Stargate. Colonel Chekov is appointed as the Russian envoy to the SGC around season 6's "Redemption" and agrees to give the Russian Stargate to the US in exchange for money, X-302 technology, and a Russian SG team. In season 6's "Disclosure", Colonel Chekov supports the US's presentation for the disclosure of the Stargate Program to the other three permanent members of the UN Security Council. In season 8's "Full Alert", Colonel Chekov helps General O'Neill deal with the possible Goa'uld compromise of the US government and establishes a direct line between O'Neill and the Russian President to avert a nuclear war. Chekov appears in season 9's "The Fourth Horseman" and "Crusade", where he has become a Russian representative of the IOA. He makes his last appearance in "Camelot" as the commander of the Earth ship Korolev to stop the Ori fleet from invading the Milky Way, but it is unknown whether he is among the six crew members to have escaped from the ship before its destruction.
Garry Chalk was assigned to the role as Chekov by executive producer Michael Greenberg and N. John Smith. They asked him if he could speak Russian, Chalk replied "No." Greenberg then replied "No matter!" And gave him his own Russian coach named Alexander Kalugin, who made an appearance in the Stargate SG-1 episode "Watergate" as one of the Russian soldiers. Portraying actor Chalk had previously worked with Richard Dean Anderson, Don S. Davis and Greenberg in 1986 on MacGyver and Smith in The Beachcombers. Greenberg had said to Chalk that they were going to bring him into the show, at first there was no audition or a single phone call, until season 5 of the series. During the shows history, Chalk "Begged" the producers for his character to go through the "Stargate", but they said no, but, eventually they came up with the idea of giving him his own starship. Chalk was the only non-Russian actor assigned in "Flesh and Blood".
Harry Maybourne 
Colonel Harry Maybourne, (played by Tom McBeath, seasons 1–6, 8) – A USAF Colonel introduced in season 1's "Enigma" as an NID member with ambiguous morals and loyalties. In season 2's "Bane", Maybourne leads an NID attempt to claim Teal'c for study after alien insect infected Teal'c. After further antagonizing SG-1 through rogue NID operations in "Touchstone" and "Shades of Grey", and helping SG-1 in "Foothold"  Maybourne flees to Russia and aids in establishing the Russian Stargate Program. He is caught in season 4's Watergate", convicted of treason, and placed on death row. O'Neill contacts Maybourne in "Chain Reaction" to help reinstate General Hammond, who was blackmailed into resigning from his position. Maybourne escapes after the mission's success and covertly helps O'Neill in season 5's "Desperate Measures" and "48 Hours" in the Adrian Conrad case. Maybourne tricks SG-1 into taking him off-world in season 6's "Paradise Lost", and is eventually exiled to a far-off planet. When SG-1 meets him again in season 8's "It's Good To Be King", Maybourne leads a life of leisure as the seemingly clairvoyant ruler of the local peoples, King Arkhan I. Although the people later discover the deception, they welcome him to stay as his technological expertise improved their standard of life, and SG-1 returns to Earth without him. He had ascended to power using an Ancient time-travelers log of his journeys into the future of the planet and ended up facing a Goa'uld invasion, but the soldiers were repelled by Jackson and Teal'c with help from one of the villagers and O'Neill destroyed in the ship in orbit, killing the System Lord behind the attack. When the team left, O'Neill and Maybourne parted amicably with Maybourne having finally accepted responsibility towards the people he was ruling over. He also revealed that he had more than one wife.
The most known character trait for Maybourne is with his ambiguous morals and loyalties. Maybourne's relationship with Jack O'Neill in the show has varied from enemy to collaborator. After his arrest, most of his cronies left Maybourne for dead in jail. O'Neill agrees to help Maybourne temporarily get out of jail, if he in turn could get General George Hammond back as leader of the Stargate Command (SGC) center. Early on on Maybourne's character development there were rumours of him being in love with Samantha Carter. It was originally planned for a scene in the series which depicted Maybourne's feelings for Carter, but the scene was cut and the relationship was never spoken about again amongst the Stargate SG-1 producers and writers alike. When portraying actor Tom McBeath was asked about the O'Neill and Maybourne relationship, he explained:
|“||"I can't stand you, but at some level I have a lot of respect for you. And I do actually, grudgingly have a good time when you're around, and things seem to work out."||”|
Tom McBeath was phoned up by his agent who said he should try to auditioning for the part as Maybourne; the audition took place in Vancouver, Canada. After auditioning for the part as Harry Maybourne, the producers revealed that he "maybe" could get a spot as a recurring character in the show. McBeath called his role as Maybourne at the start of the series "boring", but was glad for the new change in the character's direction in the series after he was convicted for treason. McBeath also commented that the writers and the producers for the show had more "fun" when his character started to "loosen" up. McBeath once stated that the character of Maybourne diminished after Richard Dean Anderson's departure from the show in season 8.
Robert Kinsey 
Senator Robert Kinsey, (played by Ronny Cox, seasons 1, 4–8) – A US senator who first appears in season 1's "Politics". In "Politics", Kinsey ignores warnings of an imminent Goa'uld invasion and instead manages to briefly shut down Stargate Command for budget reasons. In season 4's "Chain Reaction", Kinsey and the NID temporarily succeed in controlling the Stargate by blackmailing General Hammond into retirement. In season 5's "2001", Kinsey aims to gain prestige through an alliance with the Aschen, but the alliance fails. (However, the alliance went ahead in the alternate but unfulfilled future reality witnessed in season 4's "2010", in which Kinsey also achieved his goal of the presidency.) In season 6's "Smoke and Mirrors", a group controlling the rogue NID, known as "the Committee", tries to assassinate Kinsey and frame Col. O'Neill for his murder, but NID agent Malcolm Barret and SG-1 foil this attempt. Kinsey becomes Vice-President in season 7's "Inauguration" and tries again to take control of the Stargate Program in "Lost City". Shortly after NID Agent Richard Woolsey presents incriminating evidence against Kinsey to President Henry Hayes in the same episode, Hayes "accepts" Kinsey's resignation. Kinsey makes his last appearance in season 8's "Full Alert", where the SGC convinces Kinsey to go undercover to undermine the hierarchy of the Trust. However, the Goa'uld have completely infiltrated the Trust through their operatives working outside of the solar system, and have already implanted a symbiote within Kinsey to aid in their plans of starting a nuclear war between the US and Russia. After the SGC foil the attempt, Kinsey flees aboard an Al'kesh, but Kinsey's future remains uncertain as the Al'Kesh is destroyed while he operated a transport device. Kinsey is briefly mentioned as a President in the alternative timeline (with Hayes as Secretary of Defense) in season 8 finale "Moebius".
The producers of Stargate SG-1 asked Ronny Cox if he would be interested in a role in one episode, but according to Cox it was "so much fun that they and I decided we would like to do more together". According to executive producer Brad Wright, every time they got a script from an outside editor, Kinsey was included. Cox has been noted for saying that the character has become a "Malevolent force on the show". Because of the collaboration between the producers and himself. Cox described him as a "self-aggrandizing senator who like[s] to throw his weight around", and as "Kinsey feels that the Stargate [is] being used in completely the wrong way and one that is endangering American ideals and a way of life that he believes in" and a "Born-again, right-wing, Christian fundamentalist"; Cox played him as a heroic antagonist rather than villainous. Cox was approached by the producers to play Kinsey instead of auditioning himself. Kinsey holds the position of chairman of the Senate Appropriations Committee until season 7 and oversees the national defense budget of secret projects such as the Stargate Program.
Richard Woolsey 
Richard Woolsey, (played by Robert Picardo, seasons 7, 9–10) – Woolsey's first appearance is following the death of Dr. Janet Fraiser late in season 7 of Stargate SG-1, Woolsey is brought into Stargate Command in the episode "Heroes" to examine the command decisions and threatens SGC personnel with court-martial if they do not cooperate. When Woolsey brings his report to President Hayes in "Inauguration", he comes to realize Senator Kinsey's ambitions and presents incriminating evidence against him, indirectly forcing Kinsey into resigning. Woolsey returns in the season 9 episode "Prototype" and encourages the SGC to take great risks with the captured Goa'uld-human-Ancient hybrid Khalek to learn more about the Ascension process. When the studies cause injury and death among SGC personnel, Woolsey acknowledges his own error and pleads for forgiveness from the SG-1 team. Being the US's representative on the newly formed International Oversight Advisory Committee (IOA), Woolsey and some colleagues are rescued by SG-1 and the crew of the Odyssey after a catastrophe at the Gamma Site in "The Scourge", which he later considers an "eye-opening experience". Woolsey makes two more appearances in "Flesh and Blood" and "Morpheus" and last appears on SG-1 in season 10's "The Shroud". Woolsey remembers the Khalek incident and decides that Daniel, who transformed into a Prior, is too dangerous and must be placed indefinitely into stasis. However, Daniel frees himself before Woolsey's plans can be enacted.
Robert Picardo was in the main cast of Star Trek: Voyager from 1995 to 2001. He was familiar with Stargate SG-1 from his time as a Showtime subscriber. He was offered a one-day guest star as Richard Woolsey for the SG-1 episode "Heroes" in season seven (2004) while he was working on The Outer Limits in Vancouver (where Stargate SG-1 is filmed). He was then brought back for the follow-up episode "Inauguration", which began the rehabilitation of the Woolsey character. With the story introduction of the IOA, the Woolsey character made more regular appearances to "annoy people". Eventually, humor was added to the role, and the character was spun over to Atlantis as a recurring guest character. Picardo later became a main character in Stargate Atlantis.
Producer Joseph Mallozzi said that "whenever I do interviews, I often draw parallels between [Amanda Tapping and Robert Picardo]. They are both incredibly kind, professional, delightful to work with, and gifted actors who always elevate the performances of anyone they share a scene with."
Frank Simmons 
Colonel Frank Simmons, (played by John de Lancie, seasons 5–6) – The NID liaison to Stargate Command after Col. Harry Maybourne's arrest for treason. Simmons is introduced in season 5's "Ascension" and is notorious for claiming to have the best interest of the nation at heart, while really he has his own political agenda. In "Desperate Measures", Simmons shoots O'Neill in the back while O'Neill was attempting to capture a Goa'uld who has taken Adrian Conrad as host. "48 Hours" Simmons' involvement in the disappearance of the Adrian Conrad Goa'uld, whom he now holds captive, is revealed and General Hammond has him arrested. In season 6's "Prometheus", rogue NID agents hijack the unfinished starship Prometheus and demand that Simmons, along with Adrian Conrad's Goa'uld, be released. It later turns out that Simmons had orchestrated the entire affair. When Conrad is killed, the Goa'uld infects Simmons. O'Neill is able to open an emergency outer door and releases Simmons into the vacuum of space, killing him and the Goa'uld within him.
Recurring Earth ship crew characters 
- Catherine Ambrose, played by Chelah Horsdal (seasons 8–9) – A US Airforce officer of unknown rank. She takes over from Major Erin Gant as the helmsman of the Prometheus in season 8's in "New Order, Part 2" and is last seen in "Full Alert".
- Paul Emerson, played by Matthew Glave (seasons 9–10) – Introduced as the commander of the Odyssey in season 9's "Off the Grid", rescuing SG-1 and aiding in their mission to take back all stolen Stargates from Ba'al's ship. In the next episode, "The Scourge", he again rescues SG-1 and a team of the IOA from the Gamma Site. In the season 9 finale, "Camelot", Emerson teams up the Odyssey with many other ships of the Jaffa, the Asgard and the Lucian Alliance to battle the Ori battlecruisers which come through an open Supergate, and the Odyssey takes much damage. Emerson continues serving as the commander of the Odyssey in season 10 but is killed by a member of the Lucian Alliance in "Company of Thieves".
- Erin Gant, played by Ingrid Kavelaars (seasons 6–7) A US airforce Major and the first known helmsman of the Prometheus under Colonels Ronson and Kirkland as well as General George Hammond. She is first seen in "Memento" and last seen in "Lost City".
- Kevin Marks, played by Martin Christopher (seasons 9–10) – A USAF officer aboard the Prometheus introduced in "Avalon Part 1", helping Mitchell and SG-1 locate and gain access to the Ancient stronghold at Avalon. Marks is also present during the Kalana mission in "Beachhead" and the subsequent search for Gerak's hidden mothership in orbit of Earth's moon in "Ex Deus Machina", after which he is promoted to Captain. Following the destruction of the Prometheus in "Ethon", Marks is promoted to Major and becomes a Bridge officer on board the Odyssey, where he participates in various operations in "Camelot", "The Scourge, "Flesh and Blood", "Talion", and "Unending". Marks' last apparent SG-1 mission on board the Odyssey is the retrieval of the Ark of Truth from the Ori Home Galaxy in Stargate: The Ark of Truth. He takes a similar bridge position on board the Apollo in Atlantis's "Be All My Sins Remember'd" and transfers to Daedalus in "Search and Rescue". He is also last seen on board the George Hammond under the command of Samantha Carter.
- Lionel Pendergast, played by Barclay Hope (seasons 8–9) – Replaces Colonel William Ronson as commander of the Prometheus and is first seen in "New Order Part 2" patrolling Earth. Pendergast intercepts Thor's Asgard mothership Daniel Jackson after its arrival in Earth's solar system and destroys a Trust-controlled Al'kesh in "Full Alert". He is leading the search of Osiris's cloaked Al'kesh in Earth's orbit in "Endgame" and transports the Stargate and SG-1 aboard before the enemy vessel enters hyperspace. In season 9's "Beachhead", Pendergast delivers a Mark IX warhead to an Ori beachhead and maintains the ship's position during the mission despite Jaffa and Ori interruption. Pendergast dies during the destruction of the Prometheus by an Ori satellite weapon in "Ethon"; he remained aboard to beam his crew off the ship, thus saving 76 lives.
- William Ronson, played by John Novak (seasons 6–7) – A USAF Colonel and Commander of the Prometheus during seasons 6 and 7.
Other recurring Earth characters 
- Jacob Carter, played by Carmen Argenziano (seasons 2– 8) – A retired United States Air Force Major General and the widowed father of Samantha Carter and Mark Carter. Jacob Carter is introduced in season 2's "Secrets" as a USAF general dying of cancer, and after becoming a willing host of a Tok'ra named Selmak who would cure his illness ("The Tok'ra") he frequently recurs as the Tok'ra liaison to Earth. As a member of the Tok'ra High Council, Jacob/Selmak engages in Tok'ra covert operations and provides help to Stargate Command when problems arise. He goes on off-world missions with SG-1, and frequently provides valuable knowledge and expertise, including the ability to use a Goa'uld healing device. When the Earth-Tok'ra relations deteriorate, Jacob/Selmak remains the strongest link between the allies despite his loss of influence in the Tok'ra High Council. In season 7's "Death Knell", Jacob helps his daughter devise the Kull Disruptor as an invaluable weapon in fighting the army of Kull Warriors of Anubis's creation. He also plays a key role in retuning the Dakara Superweapon to the right pattern to attack the Replicators in season 8's "Reckoning", but Selmak dies of old age one episode later in "Threads", taking Jacob with him.
- Adrian Conrad, played by Bill Marchant (seasons 5–6) – A wealthy business man suffering from an incurable terminal illness and desperate to uncover the regenerative biological secrets of Goa'uld symbiotes. He hopes to learn the effects a blending had on a human by abducting Carter in "Desperate Measures", but her resistance forces him to be blended with the symbiote himself. Conrad, incarcerated under the control of Frank Simmons of the NID, unknowingly assists in freeing Teal'c from the inner workings of the Stargate in "48 Hours". Rogue NID agents are eventually able to release Conrad and Simmons from custody and escape with them aboard the hijacked and unfinished starship Prometheus. The Goa'uld desires to gain control of the Prometheus and finds its way into Col. Simmons after Simmons killed Conrad. O'Neill releases the infected Simmons into the vacuum of space through an airlock during a fight.
- Colin Cunningham (seasons 2–6, 8) – A United States Air Force Major stationed at the Pentagon. He is introduced in season 2's "A Matter of Time" and recurs in fifteen Stargate SG-1 episodes, usually aiding Stargate Command during conflicts with other nations on Earth and other portions of the United States government. He last appears in an alternate timeline in season 8's "Moebius", and makes a cameo appearance at the beginning of Stargate: Continuum. He also appeared in the Stargate Atlantis series finale, "Enemy at the Gate".
- Julia Donovan, played by Kendall Cross (seasons 6, 8–10) – A TV reporter who learns of the Prometheus program in season 6's "Prometheus" and intends to do a story on it. When she gets caught up in a rogue NID operation during her tour of the ship, she changes her mind in promised to be the first one to publish the story if and when the Stargate Program goes public. She helps cover up Stargate-related issues in season 8's "Covenant" and season 9's "Ex Deus Machina", and appears in an alternate universe in season 10's "The Road Not Taken".
- Henry Hayes, played by William Devane (season 7) – The President of the United States from season 7 onwards, introduced in season 7's "Inauguration". After Vice President Robert Kinsey and NID-agent Richard Woolsey inform him about the Stargate Program and several problems at Stargate Command, Hayes replaces General Hammond with civilian Dr. Elizabeth Weir as the new commander of Stargate Command in "Lost City". Hayes then appoints Hammond to command of the Prometheus during Anubis's actual invasion on Earth and forces Kinsey into resigning. After Anubis's defeat, Hayes puts O'Neill in command of the SGC and selects Dr. Elizabeth Weir as the leader of the Atlantis expedition. His first official visit to the SGC is alluded to in season 8's "Zero Hour", and he is mentioned again in season 10's "Bad Guys". President Hayes returns in an alternate timeline in Stargate: Continuum.
- Catherine Langford, played by Kelly Vint (girl in the film), Viveca Lindfors (elderly lady in the film), Elizabeth Hoffman (elderly lady in season 1), Nancy McClure (young woman in season 1) and Glynis Davies (middle-aged woman in season 2) – Daughter of archeologist Prof. Langford (first name never mentioned) who discovered the Stargate, as a girl she acquired an amulet depicting the Eye of Ra during the excavation of the Stargate in Giza in 1928. In present-day of Stargate, she gives the amulet to Daniel before his first mission through the Stargate to Abydos. Her fiancé, a scientist named Ernest Littlefield (played by Keene Curtis and Paul McGillion), is the first human to have travelled through the Stargate since the Ancient Egyptians buried it. Catherine and Ernest were separated by a gate incident in 1945 and were re-united in the mid-season 1 episode "The Torment of Tantalus", but Ernest is never seen again in the series (although he is mentioned in season 1s "There But For the Grace of God" and season 2's "The Fifth Race"). Catherine Langford appears again in alternate universes and times in "There But For the Grace of God" and "1969". Her death is announced in season 8's "Moebius, Part 1"; she leaves her personal collection of documents and artifacts, including the golden medallion of Ra, to Daniel Jackson.
- Rodney McKay, played by David Hewlett (seasons 5–6, 8–10) – A brilliant scientist who works with Samantha Carter in "48 Hours", "Redemption" (two-parter), "Moebius" (two-parter), "The Pegasus Project", "The Road Not Taken". Rodney McKay went on to become a main character on the spinoff series, Stargate Atlantis.
- Robert Samuels, played by Robert Wisden (seasons 1–2, 8) – A USAF Lieutenant Colonel who re-introduces O'Neill to the Stargate Program in "Children of the Gods". He repeatedly raises his concerns over the SGC's and Hammond's incompetence in "Politics" and "The Serpent's Lair". Samuels last appears in an alternate universe in season 8's "Moebius (Part 1)".
- Pete Shanahan, played by David DeLuise (seasons 7–8) – A police detective working in Denver, Colorado. He meets Carter and develops a romantic relationship with her in the late-season-7 episode "Chimera" after Carter's brother set them up. He is divorced since his previous wife could not quite cope with his work. Curious about Carter's work, he finds out about Carter's involvement with a top-secret project through an FBI acquaintance. After witnessing a fight between SG-1 and Osiris, he is given security clearance and learns the true nature of the Stargate program. Carter and Shanahan continue to see each other throughout season 7 and 8 until Shanahan proposes to marry Carter in "Affinity". She agrees, but she cancels the wedding and breaks up with him in "Threads" after he had already made wedding arrangements and was ready to buy a house.
- General Maurice Vidrine, played by Steven Williams (seasons 4, 7) A USAF General who oversaw the development and operations of Earth's fleet of spacecraft built using alien technology, including the X-301 and BC-303.
- Andy Mikita. "Proving Ground". Stargate SG-1. Season 5. Episode 13. Sky1.
- Martin Wood. "Summit". Stargate SG-1. Season 5. Episode 15. Sky1.
- Martin Wood. "Last Stand". Stargate SG-1. Season 5. Episode 16. Sky1.
- Read, David (August 2004). "Chillin' With Elliott". GateWorld. Retrieved 18 June 2009.
- "The Broca Divide". Stargate SG-1. Season 1. Episode 5. Showtime.
- "Hathor". Stargate SG-1. Season 1. Episode 14. Showtime.
- "Singularity". Stargate SG-1. Season 1. Episode 15. Showtime.
- "Heroes". Stargate SG-1. Season 7. Episode 17 & 18. Sky One.
- "Ripple Effect". Stargate SG-1. Season 7. Episode 13. Sky One.
- "2010". Stargate SG-1. Season 4. Episode 16. Showtime.
- David Read. "A Tribute to Janet Fraiser". GateWorld. Retrieved June 18, 2009.
- "Fraiser, Janet". GateWorld. Retrieved June 18, 2009.
- Carole Gordon. "From Doctor Janet to Kiss Me, Kate: Interview with Teryl Rothery". Eclipse Magazine. Retrieved June 18, 2009.
- Tobias Mauer. "Interview with Teryl Rothery". GateWorld. Retrieved June 18, 2009.
- Kate Ritter. "An Interview with Stargate's Janet Fraiser, Teryl Rothery". Richard Dean Anderson.com. Archived from the original on 2009-06-25. Retrieved June 18, 2009.
- "Children of the Gods". Stargate SG-1. Season 1. Episode 1 and 2. Showtime.
- Gilles Nuytens. "Gary Jones interview". The SciFi World. Retrieved June 18, 2009.
- Gilles Nuytens. "Interview with Gary Jones". The SciFi World. Retrieved June 17, 2009.
- D. Read. "Jonesy Encoded". GateWorld. Retrieved June 19, 2009.
- Gilles Nuytens. "Gary Jones interview". The SciFi World. Retrieved June 19, 2009.
- "Stargate". Metro–Goldwyn–Mayer (MGM) and Carolco.
- "The Enemy Within". Stargate SG-1. Season 1. Episode 3. Showtime.
- "The Gamekeeper". Stargate SG-1. Season 2. Episode 4. Showtime.
- "Point of View". Stargate SG-1. Season 3. Episode 6. Showtime.
- "Moebius". Stargate SG-1. Season 8. Episode 20. Sky One.
- Darren Sumner. "The Kawalsky Effect". GateWorld. Retrieved June 15, 2009.
- "Stargate the movie Lt. Kawalsky action figure". Amazon.com. Retrieved April 5, 2009.
- "Charles Kawalsky, Good Soldier". Stargate TCG.cz. Retrieved May 23, 2009.
- Sam Sloan. "CON Report: Secaucus Stargate CON". Slice of SciFi. Retrieved May 5, 2009.
- Eramo, Steven (July 2002). "Dan Dare – Stunt man". TV Zone (Special 46): 28–29.
- Colvin, Chad (November 2008). "Stunts and Wrenches – GateWorld talks with Dan Dan Shea". GateWorld. Retrieved June 18, 2009.
- Martin Wood. "Stargate: Continuum". Stargate franchise. Season (2008). Episode Film 3. Sci Fi Channel.
- DeLuise, Peter (2004). Audio commentary for "Death Knell" (DVD). MGM.
- Martin Wood. "Shades of Grey". Stargate SG-1. Season 3. Episode 18. Sky1.
- Brad Turner. "Tok'ra". Stargate SG-1. Season 2. Episode 9 & 10. Showtime.
- Martin Wood. "Into the Fire". Stargate SG-1. Season 2 & 3. Episode 22 & 1. Showtime.
- Martin Wood. "Lost City". Stargate SG-1. Season 7. Episode 21 & 22. Sky1.
- Peter DeLuise. "Enemy Mine". Stargate SG-1. Season 7. Episode 7. Sci Fi Channel.
- Andy Mikita. "The Road Not Taken". Stargate SG-1. Season 10. Episode 13. Sky1.
- Martin Wood. "Runner". Stargate Atlantis. Season 2. Episode 3. Sci Fi Channel.
- Peter DeLuise. "Wormhole X-Treme!". Stargate SG-1. Season 5. Episode 12. Showtime.
- Peter DeLuise. "Smoke and Mirrors". Stargate SG-1. Season 6. Episode 14. Sky1.
- Amanda Tapping. "Resurrection". Stargate SG-1. Season 7. Episode 19. Sky1.
- Martin Wood. "Ex Deus Machina". Stargate SG-1. Season 9. Episode 7. Sci Fi Channel.
- Will Waring. "Uninvited". Stargate SG-1. Season 10. Episode 5. Sci Fi Channel.
- William Waring. "Dominion". Stargate SG-1. Season 10. Episode 19. Sci Fi Channel.
- Andy Mikita. "Critical Mass". Stargate Atlantis. Season 2. Episode 13. The Movie Network.
- Andy Mikita. "Miller's Crossing". Stargate Atlantis. Season 4. Episode 9. Sci Fi Channel.
- Read, David (November 2008). "Agent Of Honor – GateWorld talks with Peter Flemming". GateWorld. Retrieved November 29, 2008.
- Peter DeLuise. "The Tomb". Stargate SG-1. Season 5. Episode 8. Showtime.
- "48 Hours". Stargate SG-1. Season 5. Episode 14. Sky1.
- Martin Wood. "Redemption". Stargate SG-1. Season 6. Episode 1 & 2. Sci Fi Channel.
- William Gereghty. "Disclosure". Stargate SG-1. Season 6. Episode 13. Sky1.
- Andy Mikita. "Full Alert". Stargate SG-1. Season 8. Episode 14. Sky1.
- Andy Mikita. "The Fourth Horseman". Stargate SG-1. Season 9. Episode 10. Sci Fi Channel.
- Robert C. Cooper. "Crusade". Stargate SG-1. Season 9. Episode 19. Sci Fi Channel.
- Martin Wood. "Camelot". Stargate SG-1. Season 9. Episode 20. Sci Fi Channel.
- "Adverse Ally". GateWorld. June 2006. Retrieved 18 June 2009.
- "Enigma". Stargate SG-1. Season 1. Episode 17. Showtime.
- "Foothold". Stargate SG-1. Season 3. Episode 14. Showtime.
- "Watergate". Stargate SG-1. Season 4. Episode 7. Showtime.
- "Chain Reaction". Stargate SG-1. Season 4. Episode 15. Sky1.
- "Desperate Measures". Stargate SG-1. Season 5. Episode 11. Showtime.
- "Paradise Lost". Stargate SG-1. Season 6. Episode 15. Sky1.
- "It's Good To Be King". Stargate SG-1. Season 8. Episode 13. Sky1.
- Read, David. "Hanging with Harry: GateWorld talks to Tom McBeath". GateWorld. Retrieved April 6, 2009.
- Jaclyn. "Tom McBeath – Characters, bad guys and… chewing gum?". The Fifth Race.net. Retrieved April 6, 2009.
- Nuytens, Gilles. "Tom McBeath interview". The SciFi World. Retrieved April 6, 2009.
- Peter F. Woeste. "Inauguration". Stargate SG-1. Season 7. Episode 20. Sky1.
- "Senator On the Rise". GateWorld. September, 2003. Retrieved June 19, 2009.
- Eramo, Steven (February 2004). "Stargate SG-1 – Ronny Cox – Politically Incorrect". TV Zone (Special #55): 64.
- Peter DeLuise. "Prototype". Stargate SG-1. Season 9. Episode 9. Sci Fi Channel.
- Ken Girotti. "The Scourge". Stargate SG-1. Season 9. Episode 17. Sky1.
- Andy Mikita. "The Shroud". Stargate SG-1. Season 10. Episode 14. Sky1.
- Sumner, Darren. "Brave New Woosley". GateWorld. Retrieved April 6, 2009.
- Mallozzi, Joseph (September 28, 2008). "September 26, 2008 Robert Picardo Answears Your Questions". josephmallozzi.wordpress.com. Retrieved June 18, 2009.