On December 5, 2011, Showtime announced that Isaac Liev Schreiber would be part of the play, playing the title character Ray Donovan of the English play.
It was confirmed on January 24, 2012 that Paula Malcolmson will play the protagonist Ray’s wife Abby.
It was confirmed on January 26 that Eddie Marsan and Dash Mihawk will play the protagonist Ray’s older brother Terry and the protagonist’s younger brother Bunche, respectively.
On February 9th, it was confirmed that Jon Voight will play the protagonist Ray's father Mickey, and Elliott Gould will play the multi-episode role Ezra is the mentor of the protagonist Ray.
It was confirmed on February 16 that Pucci Hall will play a boxer training in the Terry Boxing Gym, and Catherine Mourning will play Ray’s deputy.
It was confirmed on February 20 that Peter Jacobson will play Lee Drexler, a person who often asks Ray for help.
It was confirmed on March 2 that Jonathan Skach would play a movie star that Ray knew, Chris Dorsey as Ray’s daughter, and Ambyr Childers as a movie actor protected by Ray.
It was confirmed on March 8 that Stephen Bauer will play Avi, Ray’s next number, and Devon Bagby will play Conor, Ray’s son.
It was confirmed on February 5, 2013 that Brooke Smith will play a nurse and is Terry's love object.
It was confirmed on February 11 that Frank Huiley would play the FBI agent Van Miller, who is investigating illegal activities in Hollywood, and secretly investigate Ray.
It was confirmed on March 19 that James Woods will play the role of Patrick Sullivan in multiple episodes, which has a complicated history with Donovanga; Michael McGrady will play FBI agent Frank, who tried to investigate Ray many years ago.
It was confirmed on April 12 that Rozanna Arquette will play Linda as a guest in this series.
