One of the most watched television shows of the 1990's, "Seinfeld" is a true-to-life comedy series that follows the events of a group of friends. The group consists of Jerry Seinfeld, a stand-up comedian who questions every bizarre tidbit about life; George Costanza, a hard-luck member of the New York Yankees organization; Elaine Benes, a flashy woman and book editor who is not afraid to speak her mind; and Cosmo Kramer, an extremely eccentric, lanky goofball. Another very notable member of the show is Newman, a chubby mailman, friend of Kramer, and, almost always, nemesis of Jerry. Other sources of comedy appear in the form of the parents of both Jerry and George.
Kramer
First we have the center of the show Jerry Seinfeld. The comic that analyzes life in a sarcastic but good-hearted way. And he showed he is a great actor, some lines he delivered perfectly.
Then we have the only female main character Elaine. She is a great character but I can't compare her to the other main characters.
Then we have the genius of George Costanza. All his schemes are just great, and how he finds the most brilliant reasons to break up with his girlfriends.
Then Cosmo Kramer, a genius in his own right. Just everything he does is funny.
Cosmo Kramer was a fictional character on the United States based television sitcom Seinfeld (1989–1998), played by Michael Richards. Kramer is the wacky neighbor of main character Jerry Seinfeld. He lives at 129 West 81st Street, New York City, Apartment 5B. 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. He was once described by Elaine as "a tall, lanky doofus with a birdface and hair like the Bride of Frankenstein." His trademarks include his humorous upright bouffant hairstyle and vintage wardrobe, the combination of which led to his categorization as a 'hipster doofus'; his violent bursts through Jerry's apartment door; and his penchant for nonsensical, percussive bursts of noise to indicate skepticism, agreement, annoyance, and a variety of other inexplicable responses.
sources: wikipedia.org, imdb.com