Donald Sutherland
Those coming to the film directly from the TV sitcom may experience a shock to the system upon looking at the movie's realization of Hawkeye. Donald Sutherland looks absolutely nothing like Alan Alda, after all. Here's the kicker, however: Sutherland fits the novel's description far more accurately than does Alda. Interestingly, the more Alda-esque James Garner was seriously considered for the role, but lost out to Sutherland's intense campaigning to win the part.
Elliott Gould
MASH was one of the late 60's/early 70's hits that sent Gould for a brief period the very top of the Hollywood ladder. For a few years, Gould was as big a star as any actor making movies and his versatility was displayed in this raucous service comedy. Fortunately for all concerned, Burt Reynolds turned the part down.
Tom Skerritt
Director Robert Altman originally wanted Eliott Gould to play Duke, but his brighter star and desire to play Trapper John meant that Tom Skerritt will forever be Duke since it is the one major character from the film that never receive a transfer of duty to the TV show.
Sally Kellerman
Kellerman was the only member of unusually large ensemble cast to be nominated for an Oscar for her performance. It remains her only Oscar nomination.
Robert Duvall
With True Grit made the year before, MASH would be the launchpad out of bouncing back and forth between movies and TV for Duvall. Two years later his role in The Godfather would certify his status among Dustin Hoffman, Robert DeNiro, Al Pacino, Jack Nicholson and Gene Hackman at the top of the New Wave of 1970s superstars.
Gary Burghoff
Not only is Gary Burghoff the only actor to reprise his movie role in the legendary TV sitcom adaptation of MASH, but he also played Radar in two spinoff series: AfterMASH and W*A*L*T*E*R.
John Schuck
Perhaps better known to most people as the title character's sidekick in McMillan and Wife, Schuck also holds the distinction of being the first actor to ever spout the F-word in an R-rated movie thanks to a bit of improvisation on his part in the MASH football game sequence.