"A host of major stars are being put forward as contenders to play the Time Lord. Steve Martin, Robin Williams, Donald Sutherland, Harrison Ford, John Cleese, John Hurt, Billy Crystal, Stacy Keach and Kurt Russell are all front runners.”
Daily Express article circa 1993 on the Doctor Who casting rumors when Steven Spielberg had shown interest in the property.
Something tangentially related from the tardis wiki: “In the early 80s, Steven Spielberg was working on the blockbuster film Who Framed Roger Rabbit, one of his choices for the role of the villian, Judge Doom, was Jon Pertwee. Steve Martin, a good friend of both Spielberg and Pertwee, and one of Spielberg’s choices for the role of Eddie Valiant, advised Spielberg not to approach Pertwee for the role, because he feared that if Jon Pertwee had to choose to play a character who wanted to slaughter thousands of innocent cartoons for money or turn down his dream role (a major role in a Disney movie), it would put a terrible strain on him.”
Newspaper clipping scanned from Doctor Who Magazine (Marvel Comics Inc/1993).
Additional Roger Rabbit/Pertwee information sourced [here]