Conversation so far:
Who is Cosmo Kramer based on?
The character of Kramer was originally based on the real-life Kenny Kramer, a neighbor of co-creator Larry David from New York.
Why did co-creator Larry David use Kenny Kramer to base the character of Cosmo Kramer on?
Was Kenny Kramer a friend of co-creator Larry David's?
How were relations between co-creator Larry David and Kenny Kramer?
Larry David was hesitant to use Kenny Kramer's real name because he suspected that Kramer would take advantage of this. David's suspicion turned out to be correct.
Did Kenny Kramer agree for his name to be used for the show Seinfeld?
At the shooting of the original Seinfeld pilot, Kenny Kramer had not yet given consent to use his name, and so Kramer's character was originally known as Kessler.
Did the real life Kenny Kramer become popular from the use of his name as Cosmo Kramer on the show Seinfeld?
Kenny Kramer created the Kramer Reality Tour, a New York City bus tour that points out actual locations of events or places featured in Seinfeld.

Question: Who played Kramer in the sitcom?
Self-contained rewrite: Who played Cosmo Kramer in Seinfeld?