In his tribute to Don Rickles last week Jerry Seinfeld said that, on the Mount Rushmore of standup comedy, there are four people: Richard Pryor, George Carlin, Bill Cosby and Don Rickles.
The first two are inarguable; the last two open to endless debate. I would replace Rickles with Woody Allen, whose early, original standup work has been eclipsed by his films (and other things).