No, Doctor Doom was not originally supposed to be played by Howard Stern. The confusion may stem from the early 1990s attempts to create a film adaptation of the Fantastic Four. In 1992, producer Roger Corman and his company, New Horizons, began working on a low-budget Fantastic Four film, which was never officially released and remained largely unseen by the public until a few years ago.
The story goes that this film, directed by Oley Sassone, was created primarily to retain the film rights to the Fantastic Four, rather than for any genuine intent to release it commercially. The cast included Alex Hyde-White as Reed Richards/Mr. Fantastic, Rebecca Staab as Sue Storm/The Invisible Woman, and Julian McMahon as Doctor Doom.
Howard Stern’s name occasionally comes up in discussions about superhero films, but in this case, there’s no historical evidence to suggest that he was ever considered for the role of Doctor Doom. Stern is a well-known radio personality and television host, rather than an actor known for playing comic book villains.
The casting of Doctor Doom in the 1994 version of “The Fantastic Four” was indeed Julian McMahon, who later gained prominence for his role in the television series “Nip/Tuck.” It’s possible that confusion about the film’s history and various names associated with it could have led to the mix-up about Howard Stern’s involvement, but there’s no factual basis for the claim that Stern was originally slated to play Doctor Doom.