[QUOTE=jackdavinci]
/hijack - biographical movies in which title character plays another role/ Erin Brockovich plays a waitress in that movie.
[/QUOTE]
Along those lines, Jim Lovell played an officer on the ship that picked up the crew after splashdown in Apollo 13, which was based on his book Lost Moon.
But Stephen King undoubtedly does act in Creepshow. Whether or not you think it’s good is another matter (I do, but I’m very forgiving). It’s practically a one-man show, his segment, and he carries it. The book didn’t precede the movie, though> You could make the argument that he acted in Extreme Overdrive, which he also directed, since he had a few lines.
I don’t think Merian C. Cooper counts. He’s not the author of “King Kong” – his name doesn’t feature in the screenwriting credits at all. (He did come up with the basic idea, however) The novelization follows the movie (i.e. – the movie was an original script, not based on a book), and is by Delos W. Lovelace. Cooper and Schoedsack put themselves in as two of the pilots/gunners who shoot down Kong at the end of the film.
Ron Kovic appeared in Born on the Fourth of July as a veteran in the parade near the beginning of the the movie. He flinches when the fireworks go off, as if recalling the shot that left him wheelchair-bound. Later, when Tom Cruise, who plays Kovic, appears in a parade, he does the same.
Oliver Sacks, M.D. appeared as a reporter in At First Sight, which was based on the piece “To See and Not See” from his book An Anthropologist on Mars.
[QUOTE=jackdavinci]
/hijack - biographical movies in which title character plays another role/ Erin Brockovich plays a waitress in that movie.
[/QUOTE]
Spike Milligan played his own father in a movie based on one of his autobiographies.
Irvine Welsh plays Mikey Forrester (the drug dealer that gives Rent the suppositories and also who sells them the heroin for “the big deal”.) in Trainspotting
[QUOTE=Little Nemo]
Not a movie, but in the video game based on I Have No Mouth, and I Must Scream, Harlan Ellison provided the voice of the computer AM.
[/QUOTE]
Ellison had a bit part in the TV adaptation of his story “The Discarded” for Masters of Science Fiction.