Alec Guinness had some ambivalent feelings about shooting his role in "Star Wars" (1977), both about the campy nature of the movie, and director George Lucas's decision that his character Obi-Wan Kenobi would die only two-thirds into the story. Link to article in SlashFilm.com here.
So when Lucas wanted Guinness to appear briefly, as a ghost, in the sequel, "The Empire Strikes Back" (1980), Guiness had two demands:
- He would only be available for half a day, from 8:30am to 1:00pm (with a hard out, of course); and
- He would receive 0.25 points on the gross revenues for the movie.
That means that for 4.5 hours of work, he'd get a penny for every four dollars the movie brought in. At $400m in worldwide revenues on its initial release, that means that Guinness got $1m for that morning's work, just in the first year, not including subsequent releases, home video releases, etc.
Here is Alec, doing Acting that morning.