With reporting by Josh Horowitz

Some roles are easier to say yes to than others. As it turns out, the ultimate big bad in the Marvel Cinematic Universe is one of those roles.

Josh Brolin, at Toronto International Film Festival promoting his upcoming film "Sicario," told MTV News that saying yes to playing Thanos in "Marvel's The Avengers," "Guardians of the Galaxy" and "Avengers: Age of Ultron" was an easy decision for the actor.

"Very. I've become a guy who's like oh yeah, they offered me a part and I said no, which is not as common as we talk about it. But 'Everest' was one, Thanos was the other," he said.

"I'd turned down a lot of these things or bigger movies and immediately they sent me a huge book of all [executive producer Louis D'Esposito's] stuff because I wasn't too familiar," Brolin said of the offer to play Thanos. "I was in England doing 'Everest,' I was halfway through the book and I was like, 'I'm so in.'"

Brolin comes to set to film his scenes, most of them motion capture.

"It's really nerve-wracking but in an exciting way," he said.