Been watching Dark Side of Comedy on Vice and they've been pretty good. I saw episodes on Richard Pryor and Dustin Diamond. I never knew how much of a nutcase Pryor was, it actually disappointed me to discover how shitty he was to people in his life, particularly women.
The Diamond one was also very good. He also had a very tough life; lost his brother when he was 6, lost his mother when he was 18 if I remember right. He basically got into acting because it was the first thing he showed an interest in after his brother passed, so his father encouraged it to make him happy again. Completely understandable yet incredibly heartbreaking, especially considering how it would ultimately turn out for him.