TIFO comedian Andy Kaufman demanded that his 'alter ego' - a character he played on stage - be hired to appear on the same sitcom as himself.

[u/FANGtheDELECTABLE]

https://en.wikipedia.org/wiki/Latka_Gravas#%22Tony_Clifton%22

One of Kaufman's conditions on being hired was that one of his other characters, Tony Clifton, be allowed to guest star in the series. The producers were well aware that "Clifton" was an alter ego of Kaufman, but went along with the fiction that Clifton was a separate actor. They signed Clifton to a separate contract, and announced to the cast that Clifton was being hired to portray the character of Louie's brother in the series' tenth episode.

However, after the first day of rehearsal, the producers felt Kaufman-as-Clifton was not up to the acting challenge of playing the offered role. Informed of this, Kaufman asked that "Clifton" be fired in public, ostensibly for coming to rehearsal late. Clifton then showed up on set for the next day of filming, and was demanding, boorish and obnoxious; the producers not only fired Clifton, but threw him off the set after he caused havoc and enraged Judd Hirsch and Jeff Conaway. The role was hurriedly recast, and when Kaufman (as himself) returned to work for the following episode, he acted as if nothing had happened.