Pat Kilbane is Feldman, the Bizarro Kramer in The Bizarro Jerry (Season 8 Episode 3).
Patrick Bristow is Ethan, the Wig Master in The Wig Master (Season 7 Episode 19).
Patrick Cronin is Sid Farkus in The Sniffing Accountant (Season 5 Episode 4) and in The Doorman (Season 6 Episode 18).
Patrick Warburton is David Puddy, Elaine most dated boyfriend. He appears in 10 episodes. The first The Fusilli Jerry (Season 6 Episode 20).
Peter Crombie is Crazy Joe Davola, in five Seinfeld episodes. The first: The Pitch (Season 4 - Episode 3).
Peter Keleghan is the first Lloyd Braun in The Non-Fat Yogurt (Season 5 - Episode 7).
Phil Morris is Jackie Chiles in five episodes. The first is The Maestro (Season 7 - Episode 3).
Phillip Baker Hall is Joe Bookman in The Library (Season 3 Episode 5).
Pierrino Mascarino is Father Hernández in The Face Painter (Season 6 - Episode 22).