Bryan Cranston stars, and is quite terrific. But then pretty much all the cast is, including Diane Lane as his wife, and Ell Fanning as one of his daughters. (She doesn't come into the film until about halfway through, since she plays the grown-up teenage version of the young girl at the start.)
John Goodman also -- not shockingly -- is wonderful as a shlock producer who gives Trumbo work under-the-table when he's blacklisted, and has one especially wonderful scene where...well, let's just say it's when a blacklist alliance member comes to discuss Trumbo's employment. And somewhat surprisingly, another standout and lovingly underplayed performance is given by Louis C.K. as a fellow-blacklisted writer.
As I said, most of the cast is very good, including Helen Mirren as Hedda Hopper, and there are other fun performances of real-life people, including John Wayne, Louis B. Mayer, Kirk Douglas, Otto Preminger, and Edward G. Robinson.
The film was wonderfully written by John McNamara, his first feature film, though he's written some TV movies, and a great deal for television series, and very well-directed by Jay Roach, who did Meet the Fockers, Austin Powers and several political-theme films, like HBO's, Game Change and Recount. (Upcoming, he directed, All the Way, based on the Broadway play about LBJ that starred Bryan Cranston, who repeats his performance.)
Here's a very good 4-minute feature about the movie, that gives a pretty good sense of it. (One of the people interviewed is Nikola Trumbo, who is the woman that Elle Fanning plays as a young girl.)