He is best known for his roles as Milton Mamet in the third season of AMC's The Walking Dead (2012–2013), Eliot Delson in Unforgettable, and Owen Cavanaugh in The Good Wife.

[citation needed] Roberts' film work includes the screen adaptation of Michael Cunningham's A Home at the End of the World, and supporting roles in Walk the Line and The Notorious Bettie Page, among others.

[6] He starred in the AMC original series Rubicon as Miles Fiedler, a genius intelligence analyst at a national think tank.

[7] He appeared in twelve episodes of The Good Wife as Owen, the gay brother of Alicia Florrick (Julianna Margulies).

[10] From August 2012 through March 2013, Roberts was in the cast of The Walking Dead as scientist Milton Mamet, who studies "walkers" (zombies).