- The Odd Couple was, I believe, a Neil Simon play, before it became a film,
and then a sitcom.
- Robocop and Highlander are recent examples of film to TV series.
- I'm sure someone wiser than I will be able to tell you if the film of MASH
came before the sitcom. I think it did, but could be wrong.
Good luck with it. I hope these are of some help.
Best wishes,
Screen-L is sponsored by the Telecommunication & Film Dept., the 
University of Alabama.