The Seinfeld theme song is the one with the slap bass music backed by a mouth of percussive noises. It is greatly associated with the show, and has become one of its signatures. The song was composed by American composer Jonathan Wolff, who also worked on Perfect Strangers, Will & Grace, and King of Queens.
The theme is included in NBC: A Soundtrack Of Must See TV, released by TVT Records.
The video below showcases said song during the opening credits of Seinfeld’s 100th episode.