Richard Pryor, R.I.P.
I haven't seen it in eons, but Silver Streak (amazon link) was hilarious last time I saw it. I was in high school then, so YMMV. The IMDb claims he almost played the sheriff in Blazing Saddles, and it's too bad he didn't. Not much could improve that movie, but I expect Pryor could.
We can only hope than Heaven has a place for foul-mouthed, drug using comic. It wouldn't be worth it otherwise.
According to Pryor Convictions, Groucho Marx got him to be more wild and personal with his act by telling him:
Do you want a career you’re proud of, or do you want to end up a spitting wad like Jerry Lewis?Words to remember.