Sam Rockwell always wanted to do ''darker stuff''.

The 49-year-old actor has starred in a number of comedy rolls but admitted he also enjoys playing more serious roles and is set to portray George W Bush in Adam McKay's Dick Cheney biopic.

Speaking to The Guardian newspaper, Rockwell said: ''I've always wanted to do darker stuff, but I like to be silly too.

''Though comedy also takes it out of you. I mean, it's not digging ditches, but mentally.

''You do 16-hour days, with a deadline. Working with Adam McKay and playing George W Bush, with Christian Bale as Dick Cheney... that's responsibility, you know? You gotta have a beer at the end of the week.''

Rockwell is now starring alongside Frances McDormand and Woody Harrelson in the new Martin Mcdonagh movie 'Three Billboards Outside Ebbing, Missouri', and he has nothing but praise for the filmmaker.

He said: ''I put him [McDonagh] up there with David Mamet, Quentin Tarantino, Harold Pinter, Sam Shepard, Kenny Lonergan.

''His writing is astounding. And now he's this amazing film director. He's made three pretty f**king good movies, and this is probably his best.

''I'm not embarrassed to tell you I've seen it more than once. I'm so proud of it.

''It's easy, working with Martin. I'll be nervous to read in front of him for the first time.

''I work with coaches and do my homework, so I'm usually pretty prepared. Then he'll make little adjustments like the hair. But it's never, like, 'you're way off the mark'.

''He casts the right people, ultimately.''

Rockwell won the Supporting Actor award at the Golden Globes on Sunday (07.01.18) and has been nominated for a BAFTA for his role as Jason Dixon in the new movie and said he enjoys ''rubbing shoulders'' with other celebrities.

He said: ''It's fun. It's nice to get props, but you can take the piss out of it all at the same time.

''There are moments of enjoyment when you're rubbing shoulders with a mentor like Gary Oldman.

''That's a kick. Tom Hanks, who I've worked with. Meryl Streep. Judi Dench.''