Vincent Crabbe – Slytherin student in Harry's year, son of Death Eater, Slytherin Quidditch team Beater, member of the Inquisitorial Squad, friend of Draco Malfoy.
Colin Creevey – Muggle-born Gryffindor student one year below Harry, brother of Dennis Creevey, member of Dumbledore's Army, killed during the Battle of Hogwarts, after sneaking away from the younger evacuated students in the seventh book
Dennis Creevey – Muggle-born Gryffindor student three years below Harry, brother of Colin Creevey, member of Dumbledore's Army
Dirk Cresswell – Muggle-born Head of the Goblin Liaison Office, went on the run in Deathly Hallows with fellow muggle-born Ted Tonks, Dean Thomas and goblins Gornuk and Griphook.
Cornelius Fudge – Minister for Magic in the first five books, sacked when he denied Lord Voldemort's return for a year.
Marvolo Gaunt – Pure-blood father of Merope and Morfin Gaunt, grandfather of Tom Marvolo Riddle.
Merope Gaunt – Daughter of Marvolo Gaunt, sister of Morfin Gaunt, wife of Tom Riddle Sr, mother of Tom Marvolo Riddle/Lord Voldemort, died after childbirth, named for Merope, one of the Pleiades, who married a mortal
Morfin Gaunt – Son of Marvolo Gaunt, brother of Merope Gaunt, uncle of Tom Marvolo Riddle, framed by his nephew for Muggle killings.
Rubeus Hagrid – Half-giant keeper of Keys and Grounds at Hogwarts, Care of Magical Creatures professor starting from Harry's third year, member of the Order of the Phoenix. Once a Hogwarts student, Hagrid was expelled in his third year.
Ernie Macmillan – Hufflepuff student in Harry's year, school prefect, member of Dumbledore's Army
Minerva McGonagall – Hogwarts Transfiguration professor, Head of Gryffindor House, Deputy Heamistress of Hogwarts, member of the Order of the Phoenix.
Alastor "Mad-Eye" Moody – Retired Auror, member of the Order of the Phoenix, impersonated by Barty Crouch Jr. in 'The Goblet of Fire'
Theodore Nott - Slytherin student in the same year as Harry Potter. Nott is one of the few students who can see Thestrals, suggesting that he has witnessed a death at some point. His father is a Death Eater, and described as an elderly widower.
Pansy Parkinson – Slytherin student in Harry's year, school prefect, member of the Inquisitorial Squad, Draco Malfoy's girlfriend for some time.
Padma Patil – Ravenclaw student in Harry's year, identical twin sister of Gryffindor Parvati Patil, member of Dumbledore's Army.
Parvati Patil – Gryffindor student in Harry's year, identical twin sister of Ravenclaw Padma Patil, member of Dumbledore's Army.
Peter Pettigrew – Former school friend of James Potter, Sirius Black and Remus Lupin. Betrays James and Lily Potter. Death Eater, an unregistered animagus, Pettigrew is first introduced as a rat known as Scabbers.
Antioch Peverell – Original owner of The Elder Wand in The Tale of the Three Brothers.
Cadmus Peverell – Original owner of The Resurrection Stone in The Tale of the Three Brothers
Ignotus Peverell – Original owner of The Invisibility Cloak in The Tale of the Three Brothers.
Demelza Robins — a student at Hogwarts School of Witchcraft and Wizardry, sorted into Gryffindor House. She was a Chaser for the Gryffindor Quidditch team, and was noted to be particularly skilled at dodging Bludgers.
Severus Snape – Hogwarts, Potions and later Defence Against the Dark Arts professor, Head of Slytherin House, a member of both the Death Eaters and the Order of the Phoenix.
Alicia Spinnet – Chaser on the Gryffindor Quidditch team, two years above Harry Potter at Hogwarts. Member of Dumbledore's Army.
Pomona Sprout – Hogwarts Herbology professor, Head of Hufflepuff House.
Pius Thicknesse – Minister for Magic while under the Imperius Curse, later replaced by Kingsley Shacklebolt.
Dean Thomas – Gryffindor student in Harry's year, member of Dumbledore's Army, briefly Ginny Weasley's boyfriend, Gryffindor Quidditch Chaser.
Andromeda Tonks – Sister of Bellatrix Lestrange and Narcissa Malfoy, disowned by her family for marrying Muggle-born Ted Tonks, mother of Nymphadora Tonks.
Nymphadora Tonks – Daughter of Ted and Andromeda Tonks, auror and member of the Order of the Phoenix. She marries Remus Lupin, and become mother of Teddy Lupin.
Ted Tonks – Muggle-born husband of Andromeda and father of Nymphadora Tonks.
Travers — was a wizard and a Death Eater. Escaped from Azkaban after Lord Voldemort's return.
Sybill Patricia Trelawney – Hogwarts Divination professor, predicted the prophecy that prompted Lord Voldemort to go after the Potters
Dolores Jane Umbridge – Senior Undersecretary to the Minister for Magic, Defence Against the Dark Arts professor, Hogwarts High Inquisitor, Headmistress of Hogwarts, who enthusiastically joins in the persecution of half-bloods under Voldermort.
Emmeline Vance - a member of the party that brings Harry to Grimmauld Place, member of the Order of the Phoenix. Described as "A stately looking witch in an emerald green shawl".
Lord Voldemort – The villain of the series, murderer of Harry Potter's parents and many others in his quest for immortality and absolute power.
Arthur Weasley – Muggle-obsessed Ministry of Magic employee. Husband of Molly Weasley, father of Bill, Charlie, Percy, Fred, George, Ron, and Ginny Weasley, member of the Order of the Phoenix
Bill Weasley – Oldest son of Arthur and Molly Weasley, Gringotts employee.
Charlie Weasley – Second son of Arthur and Molly Weasley, and member of the Order of the Phoenix, works with dragons in Romania.
Fred Weasley – Son of Arthur and Molly Weasley and identical twin brother of George Weasley, member of Dumbledore's Army, Gryffindor Quidditch Beater, co-owner of Weasleys' Wizard Wheezes, killed in an explosion caused by Augustus Rookwood in the Battle of Hogwarts.
George Weasley – Son of Arthur and Molly Weasley and identical twin brother of Fred Weasley, member of Dumbledore's Army, Gryffindor Quidditch Beater, co-owner of Weasleys' Wizard Wheezes, marries Angelina Johnson
Ginny Weasley – Only daughter and youngest child of Arthur and Molly Weasley, Gryffindor student one year under Harry, Gryffindor Quidditch Seeker and Chaser, member of Dumbledore's Army.
Molly Weasley (née Prewett) – Wife of Arthur Weasley, mother of Bill, Charlie, Percy, Fred, George, Ron and Ginny Weasley, member of the Order of the Phoenix.
Percy Weasley – Third son of Arthur and Molly Weasley, Gryffindor prefect and Head Boy then Ministry of Magic employee, long estranged from his family before joining them against the Death Eaters in Deathly Hallows,
Ron Weasley – Harry's close friend, youngest Son of Arthur and Molly Weasley, Gryffindor Quidditch Keeper, school prefect, member of Dumbledore's Army.
Oliver Wood – Hogwarts student, Gryffindor Quidditch Keeper and captain.
Kennilworthy Whisp - author of "Quidditch Through the Ages"
Yaxley – Death Eater, Head of Magical Law Enforcement under Voldemort's regime.
Blaise Zabini – Slytherin student in Harry's year, friends with Draco Malfoy.
Characters with no or unknown surname
Aragog – Acromantula raised by Rubeus Hagrid, lives in the Forbidden Forest.
Kreacher – House-elf belonging to the Black family, and later Harry Potter. Though at first preferring to serve the pureblood line (including Regulus Black, Narcissa Malfoy, Bellatrix Lestrange, and Draco Malfoy), he eventually likes serving under Harry as he treats him better.