I think I remember something on one of the DVD commentaries, Jonathan Frakes saying “Old Star Trek actors don’t die, they just do voices on Gargoyles.”

Still sad Stewart never voiced a role.

He wanted to, but the studio couldn’t afford him and he couldn’t reduce his asking price because it’d breach a contract somewhere or something.

This is often sad and true.  Theirs alot of roles Actors would like to play, but can’t due to contracts say they have to get paid so much once they become really famous.  Its like they first have to stave to get the pay, but once they get the pay they can no longer have fun and play. :/