I am shocked and chagrined, mortified and stupefied! :mad:
The TV show Bull is a highly fictionalized take on the life of Phil(Dr. Phil) McGraw, who created the show. Bull’s “Trial Analysis Corporation” is based on Dr. Phil’s Courtroom Sciences, Inc.
George Steinbrenner, not George Costanza. Larry David voiced Steinbrenner on early episodes, but later Steinbrenner himself made a cameo.
I wonder if Friday and his bunch knew they were living in a simulation.
Jason Alexander started out doing a Woody Allen impression, but as time went by he based George Costanza more on Larry David, mainly because of Larry writing so much of his material. I saw a clip from Curb Your Enthusiasm the other day where they were arguing about this, with Larry saying something like “Don’t tell me I couldn’t have you do that. Exactly the same thing happened to me!”
If you watch the behind-the-scenes videos from ***Seinfeld ***on YouTube, the actors talk a lot about how their different characters developed.
Speaking of George Costanza, a few years ago Jason Alexander played Tony Kornheiser in a show that lasted about 5 minutes.
We never saw John-John, did we? We just heard his voice. 
I liked the reference on Corner Gas when Oscar wanted to watch Pretty Woman (I think it was) on his VCR: "It’s got that guy from ***Seinfeld ***in it!
“Fat Albert and the Cosby Kids” included childhood versions of Bill Cosby and his brother Russell, as well as, supposedly, other kids from their neighborhood. Back when everybody loved Bill Cosby.
Louis C. K. played himself on Louie.
On King of Queens Lou Ferrigno played himself as the Heffernan’s neighbor.
The OP makes no such restriction, and in fact the examples he uses are of this kind.
Nitpick: It’s Chiles, not Childs. 
He also played Adam West on an episode of Big Bang Theory.
How about The Monkees?
I’m not sure if this counts or not but in one episode of Star Trek:The Next Generation Data plays cards on the Holodeck with holographic representations of Sir Isaac Newton and Stephen Hawking. Hawking played himself in the episode; he was the only person to play himself in the history of the Star Trek franchise.
You know Erica Goldberg? She’s loosely based off of Dr. Eric Goldberg, my mother’s headache doctor. True story; he told that to us last time we were there.
It’s sort of the other way. The fictional persons became living people.
Feels like someone should mention That’s My Bush!
Boston Legal did the same thing twice. Arguments went before the SCOTUS and the justices matched up exactly with the current real-life ones.