Everett Sloane appeared as Jubal Foster, the farmer/moonshiner in "The Keeper of the Flame". He also composed the lyric for the show's theme song; Griffith sang them on the show's soundtrack album, but the lyrics were never used on the show. Sloane is known for his role as Mr. Bernstein in Citizen Kane.
Bo Hopkins played George in "Goober the Executive."
Allan Melvin played different characters in eight episodes of The Andy Griffith Show. On the spin-off, Gomer Pyle, he was Sgt. Carter's rival, Sgt. Hacker, the mess cook. Melvin is also noted for his roles as Sam Franklin on The Brady Bunch and Barney Hefner on All in the Family. In addition, Melvin directed some episodes of Andy Griffith, including Don Knotts' return appearance in 1966, "The Return of Barney Fife".
Larry Hovis played Gilly Walker in "Goober Takes a Car Apart" and "The Case of the Punch in the Nose." Hovis played Pvt. Larry Gotschalk on Gomer Pyle as well as Sgt. Andrew Carter on Hogan's Heroes.
Frank Cady played a drunk inmate named Luke in "The Rehabilitation of Otis" and Farley Upchurch in "The Legend of Barney Fife." Cady is best known for playing Sam Drucker on Green Acres. He also played the town drunk in the episode of Make Room for Daddy which was the pilot episode of The Andy Griffith Show.
Hank Patterson played a hobo in "If I Had a Quarter Million Dollars." Patterson is best known for playing farmer Fred Ziffel.
Mary Grace Canfield played Mary Grace Gossage in "A Date for Gomer." She portrayed Ralph Monroe.
Jamie Farr played a gypsy con man named Sylvio in "The Gypsies", Season 6. Farr's most famous role is Max Klinger.
William Christopher played Dr. Peterson in "A New Doctor in Town" and an IRS agent Mr. Heathcoat in the episode "Aunt Bee on TV" Christopher is best known for his role as Father Mulcahy. He also played Private Lester Hummel on Gomer Pyle: U.S.M.C.
Jerry Van Dyke played bumbling musician Jerry Miller in "Banjo-Playing Deputy". He was considered as a permanent replacement for Don Knotts, who left at the end of season 5. However, Van Dyke opted to take a starring role in the flop TV series My Mother The Car instead. Years later, Van Dyke said he wished he had accepted the offer. He later portrayed Luther Van Dam on Coach.
Gavin MacLeod played Sheriff Taylor in the Hollywood version of "Sheriff Without a Gun" in "Taylors in Hollywood" and a bank robber in an earlier episode "Crime Free Mayberry". MacLeod also starred as Capt. Merrill Stubing in The Love Boat and as news writer Murray Slaughter on The Mary Tyler Moore Show.
Don Rickles played traveling salesman Newton Monroe in "The Luck of Newton Monroe".
Laurie Main played assistant publisher Robling Flask in "Helen, the Authoress." Main is best known for hosting and narrating for Welcome to Pooh Corner, as well as narrating for many "Disney Read-Along" records and cassettes.