Hunter S. Thompson (1 episode)

Sipple

John Sirica (2 episodes)

Javier

Commissioner Milo

Self (2 episodes)

David

Tolly (1 episode)

Tree

Veebie

Detective Eddy Costa (14 episodes)

Dormit (1 episode)

Red Briles

A Team Leader

Lou Meshejian (1 episode)

Harry Magarac (1 episode)

John

Father Merrino

Taxista

Gary Prima (5 episodes)

Jack Marchiano

(13 episodes)

Valenti

Bobby Navarro (1 episode)

Self

Jackson

General Humberto Delgado

Christopher Zambrano (1 episode)

Justin Malik (25 episodes)

Mickey Scicoli

Shrink

Drazen

Dino Arbogast (16 episodes)

Man #1

Weinstein

Self (1 episode)

Burrelli (1 episode)

Theo Horace / Horatio

Hero Furillo

John Constantin

Ronald Hawk (1 episode)

Stanley Vespucci (1 episode)

Justin

Dr. George

Writer

Gabe

Nicky Singer

Narrator (voice)

Hank Bartlowski at 33

Dispatch Operator (as John Ventimiglia)

Raymond Pelagi

McInnes

Johnny Graziosi

Anton

Louie Salazar

Artie Bucco (37 episodes)

Newark Cab Driver

Larry

Alvin

Tony the Pizza Guy

Doug

Man at Party

Officer V

Joey / Cop

Det. Manning

Eddie

Johnny

John Who Likes Lesbians

Sali

Andrew

Tea Dance Bouncer

Tough Guy

Driver

Manuel (1 episode)

Waterfront Hood

Mr. Dibbens (2 episodes)

Gaydos (1 episode)

Nick Capetti (1 episode)

Officer Frank Dietrich (1 episode)

Angel

Band Member #1 (uncredited)