One of Seinfeld's most remarkable qualities is how grounded it is in real life. Unlike many sitcoms, which construct characters from scratch, Seinfeld drew almost all of its central figures directly from people Jerry Seinfeld and Larry David actually knew. The show's famous "show about nothing" philosophy was rooted in something concrete: these were real people, these were real situations, and the comedy came from recognising both.
George Costanza is Larry David. This is not a subtle influence or a partial inspiration — it is an almost complete transfer of personality, biography, and worldview from one man to a fictional character. David has confirmed in numerous interviews that George's most outrageous storylines — the job quitting and re-entering as if nothing happened, the contest, the rage at perceived slights — are drawn directly from his own life.
Jason Alexander, who played George, spent time studying Larry David before filming to understand the specific quality of his energy. David's own later HBO series Curb Your Enthusiasm essentially continued the George character under a different name, making explicit what Seinfeld had always implied: George Costanza is what happens when Larry David plays himself.
Kramer is based on Kenny Kramer, Larry David's actual next-door neighbour in his Manhattan apartment building. The real Kenny Kramer was a musician, inventor, and self-described entrepreneur who had an open-door relationship with David — wandering into his apartment, sharing half-formed business ideas, living with an enthusiasm for life that David found both amusing and exhausting.
The real Kenny Kramer later capitalised on his status as the inspiration for one of television's greatest characters by launching the Kramer Reality Tour — a bus tour of New York sites related to the Seinfeld character. He has said the character made him famous in ways he could never have anticipated and that he bears no resemblance to the fictional version, which is itself a very Kramer thing to say.
Newman is less directly biographical but is drawn from a type Larry David recognised from his own apartment building experience — the aggressively mediocre neighbour whose self-regard is entirely disconnected from his actual circumstances. The specific character of Newman was developed for the show, but the template of the self-important postal worker with a grudge against the world is rooted in real observation.
Wayne Knight, who played Newman, has said he based the character partly on people he had known who had that particular quality of believing themselves to be misunderstood geniuses temporarily trapped in unsuitable situations.
Jerry is the show's only character who is played by his real-world inspiration, which creates a unique situation in television history. The fictional Jerry shares the real Jerry's name, profession, apartment building, general social circle, and many of his actual opinions and observations. The stand-up sequences at the beginning and end of each episode were performed by the real Jerry Seinfeld doing his actual stand-up material.
This blurring of reality and fiction was deliberate. The show wanted to feel grounded, and having its central character be a version of the show's creator gave it an authenticity that pure fiction cannot achieve.
Elaine is the show's most composite character — drawn not from a single person but from several women in Larry David's life. Her professional ambition, her romantic frustrations, and her specific quality of being equally capable of bad behaviour as the men around her were all observed traits rather than invented ones. Julia Louis-Dreyfus has said that she brought considerable amounts of herself to the role as well, making Elaine the character most shaped by the actor who played her.
The Soup Nazi is based on a real person: Al Yeganeh, the owner of Soup Kitchen International in midtown Manhattan, who was famous in New York food circles for his extraordinary soup and his impatience with customers who did not follow his precise ordering protocol. Yeganeh was reportedly furious about the episode and the "Soup Nazi" nickname, which he felt was disrespectful and hurtful. He has since sued over uses of the name and image, making him one of the few real-world Seinfeld inspirations who did not embrace his connection to the show.