John D'Aquino is Todd Gack in The Calzone (Season 7 Episode 20).

John Del Regno is Manager in The Busboy (Season 2 Episode 12).

John F. O'Donohue is Gus in The Beard (Season 6 - Episode 15).

John Gabriel is the Newscaster in The Non Fat Yogurt (Season 5 Episode 7).

John Hillner is Greeny in The Revenge (Season 2 Episode 7).

John Kapelos is Barry Prophet, the sniffing accountant in The Sniffing Accountant (Season 5 Episode 4).

John Lizzi is the other guy (the third tenor) in The Doll (Season 7 - Episode 16).

John Michael Higgins is Kurt, Elaine's boyfriend in The Little Jerry (Season 8 Episode 11).

John O’Hurley is Jacopo Peterman. He appears in 20 episodes. The first is The Understudy (Season 6 Episode 23).

John Paragon is Cedric in 3 episodes. First: The Soup Nazi (Season 7 Episode 6).

John Posey is Dr. Fein (Dr. Tongue) in The Heart Attack (Season 2 Episode 8).

John Putch is Roy in The Stranded (Season 3 Episode 10).

John Randolph was the first Frank Costanza in the original version of The Handicap Spot (Season 4 Episode 22).

John Riggi is Bank Teller in The Invitations (Season 7 Episode 22).

John Rubano is Man in The Postponement (Season 7 Episode 2).

Johnny Silver is Ice Cream Vendor in The Understudy (Season 6 Episode 4).

Jon Favreau is Eric, the clown in The Fire (Season 5 Episode 20).

Jon Gries is Homeless Man and Rusty in The Beard Jerry (Season 6 Episode 15) and The Bookstore (Season 9 Episode 17).

Jon Lovitz is Gary Fogel, George's and Jerry's friend in The Scofflaw (Season 6 Episode 13).

Jon Manfrelotti is Guy in Police Lineup in The Beard (Season 6 Episode 16).

Jon Polito is Silvio in The Reverse Peephole (Season 9 Episode 12).

Jon Voight is Jon Voight in The Mom and Pop Store (Season 6 Episode 8).

JoNell Kennedy is Secretary in The Nap (Season 8 Episode 18).

Joseph Maher is Gavin Pollone in The Dog (Season 3 Episode 4).

Joseph Malone is Michael, Robin Sandusky's husband in The Good Samaritan (Season 3 - Episode 19).

Joseph R. Sicari is Willie in The Secretary (Season 6 Episode 9).

Joseph Ragno is Marty in The Wife (Season 5 Episode 17).