Alan Oppenheimer is an American character actor and voice actor. He has performed numerous roles on live-action television since the 1960s, and has had an active career doing voice work in cartoons since the 1970s.

He is recognised as the voice of many characters, often for Filmation in the 1970s and 1980s, such as Mighty Mouse, Ming the Merciless on Flash Gordon, the Overlord on BlackStar, and Skeletor, Man-At-Arms and Mer-Man from Filmation's 1980s cartoon He-Man and the Masters of the Universe. Other notable voice roles include Thundarr the Barbarian, Vanity on The Smurfs, Rhinokey and Crock from The Wuzzles and Falkor and Gmork from 1984's The NeverEnding Story. In the early 1990s, Oppenheimer was the voice of Merlin in The Legend of Prince Valiant. He also performed various supporting roles in various incarnations of Scooby-Doo. He took over the voice of Roger Smith's butler Norman Burg in the second season of The Big O. Oppenheimer also worked on The Transformers, most notably as two contrasting characters, the pacifist Beachcomber and the bellicose Warpath. His rendition of Seaspray was remarkably similar to Mer-Man, including the gurgling effects. He was the voice of Alistair Crane on the soap opera Passions up until 2004 (when the character was made fully visible, played by David Bailey). Oppenheimer recently provided the voice of the Scientist for the 2009 film 9.

Oppenheimer's repertoire also includes video games, voicing Dr. Piotr Ivanovich in Soldier of Fortune II: Double Helix, Prometheus in God of War II and Jandor the Airship Captain in Nox. In Fallout: Brotherhood of Steel, he spoke the part of Harold, an ancient mutated survivor of nuclear holocaust who has appeared in four of the Fallout series games. Oppenheimer also voiced the parts of a non-player character Soldier and the Wasteland Trader, and the NPC 'enemies' Cult Ghoul Thug and Kamikaze in Fallout: BoS. Also, in the 1990-1992 compilation of Ys Book I and II, Oppenheimer voiced the roles of the Narrator, and the game's lead antagonist, Darm. In Superman/Batman: Public Enemies he had a brief role as Batman's butler, Alfred Pennyworth.