I heard Joel on the radio before Community and I thought he said he only became a stand-up after his agent showed him how much he could earn because of his fame on the Soup. So, he is doing an act, but is an actor and presenter first.
Saget isn’t a particularly good stand up comic. He basically free forms with the audience, trying to work in really outrageous/offensive comments that might make the audience laugh out of disbelief.
I saw him many years ago in Scotland, when he was using the stage name Bing Hitler. He was very funny, but wired to the moon. I don’t think it was just the drink he had a problem with.
I came in to mention Bob Newhart. I think he was the first standup comedian to get a television series; I used to listen to his comedy records - very funny.
His 1961 show predates any others I can think of offhand. You could credit Groucho Marx with this, but he I don’t know if he ever billed himself as a standup comic though he often filled that role.
Jim Davidson, a successful, but very ‘seventies’ UK comedian played a straight role in Peter Greenaways “A Zed and Two Noughts”. Bizarre, even for that rather bizarre film…
He wrote an autobiography (which I have also read - “American On Purpose”) where he talks about his checkered past. It doesn’t sound like he had many limits on his debauchery.