Revolving around the lives of an army medical unit during the Korean War, M*A*S*H started out as a 1970 film by Robert Altman. Starring such luminaries as Donald Sutherland and Elliott Gould, the film had a very biting sense of dark humor, and was as much a drama as it was a comedy.
When it came time to bring M*A*SH* to TV, the harsh satirical edge of the humor was lessened, and the characters made more likable. The series went on to run for over a decade, becoming a cultural touchstone along the way.
When people think of "Hawkeye" Pierce, they think of Alan Alda, not Donald Sutherland. Some people don't even know there was a movie. With a finale watched by over 125 million people, M*A*S*H remains the quintessential example of a TV adaptation done right.