Michael Shannon as Richard Kuklinski

Winona Ryder as Deborah Kuklinski

Ray Liotta as Roy Demeo

Chris Evans as Robert Pronge

David Schwimmer as Josh Rosenthal

James Franco as Marty Freeman

Stephen Dorff as Joey Kuklinski

Robert Davi as Leo Marks

John Ventimiglia as Mickey Scicoli

Danny A. Abeckaser as Dino Lapron

Ryan O'Nan as Terry Franzo

McKaley Miller as Anabel

Hector Hugo as Tender Bar Earl

Zoran Radanovich as Jimmy

Shira Vilensky as Coffee Shop Waitress

Kelly Lind as Hospital Nurse

John P. Fertitta as Uncle Bill

Erin Cummings as Ellen

Jimmy Lee Jr. as Homeless Man

Johnny Martin as Mareilli

Nick Gomez as Alvaro

Vincent Fuentes as JC

Brian Kinney as Slick BMW Guy

Ashlynn Ross as Alex

Weronika Rosati as Livi

Christa Campbell as Adele

Alexandra Doke as Park Little Girl

Bill Martin Williams as Club Maitre D'

Lindsay Clift as Club USA Dance Partner

Katarzyna Wolejnio as Romy

Jay Giannone as Dominick Provenzano

Freddy Bosche as Detective Beaumont

Tim Bell as Cop

Garrett Kruithof as Stanley Kuklinski

Ray Gaspard as Dennis

Juan Michael Konshuk-Mas as Mr. Freezy's Son

Ehud Bleiberg as Trial Judge

Jonathan Vender as Trial Judge (voice)

Tommy Alastra as

Tommy Alastra as Documentary Interviewer (voice)

Gavin Casalegno as Roller Skater (uncredited)

Joy Leigh as Restaurant Patron (uncredited)

Víctor Quintero as Hanging Corpse