Cosmo Kramer, usually referred to as simply "Kramer", is a fictional character on the American television sitcom Seinfeld (1989-1998), played by Michael Richards. The character is loosely based on comedian Kenny Kramer, Larry David's ex-neighbor across the hall. Kramer is the friend and neighbor of main character Jerry, residing in Apartment 5B, and is friends with George and Elaine. Of the series' four central characters, only Kramer has no visible means of support; what few jobs he holds seem to be nothing more than larks.
Inspiration
The character of Kramer was originally based on the real-life Kenny Kramer, a neighbor of co-creator Larry David from New York. However, Michael Richards did not in any way base his performance on the real Kramer, to the point of refusing to meet him. This was later parodied in "The Pilot" when the actor that is cast to play him in Jerry and George's sitcom refuses to base the character on the real Cosmo Kramer. At the time of the shooting of the original Seinfeld pilot, "The Seinfeld Chronicles," Kenny Kramer had not yet given consent to use his name, and so Kramer's character was originally known as "Kessler."  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; 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. The "Kramer Reality Tour" is itself spoofed on Seinfeld in "The Muffin Tops." In the episode, when Kramer's real-life stories are used by Elaine to pad the biography of J. Peterman she was ghostwriting, he develops a reality bus tour called "The Peterman Reality Tour" and touts himself as "The Real J. Peterman," even though, as Jerry notes, reality is the last thing Kramer is qualified to give a tour on.  Richards' physicality can be seen in his early 1980s appearances on The Tonight Show, the early 1980s ABC sketch comedy show "Fridays", and his appearance in the film "Young Doctors in Love" where he plays a hit man; a nod to this appears in the "Air Conditioner" episode.

Q: What was his inspiration?
A: The character of Kramer was originally based on the real-life Kenny Kramer,
Was he in a tv show?
unknown
unknown