Richard Pryor would have been 72 years old yesterday. If you are making any top comedians list of all time he is going to be on that list. I found this great collection of clips of him. Look at the first from 1964 even if you don't watch the rest. So different from his later standup.
Source:
http://www.crazydaysandnights.net/2012/12/richard-pryor.html