It's no longer a secret -- open or otherwise -- that Josh Brolin is playing Thanos in the Marvel Cinematic Universe, making his first appearance in this weekend's Guardians of the Galaxy. But of all the actors who could've played the part, why did director James Gunn want Brolin as the Mad Titan?

"Thanos needed to be this imposing character. He needed to have weight to him," Gunn told Vulture. "So it was about finding the right person to fulfill that role, and we actually auditioned a lot of people for Thanos. That role really is a big commitment, because as everyone has guessed, Thanos is a big part of the Marvel universe going forward, and his role is likely to expand greatly. It was a big challenge to cast."

"He is great for the movie," the director added of Brolin, in a separate interview with IndieWire. "I don't think he knew what he was getting into. I think he's overwhelmed by all the attention he's getting for Thanos. And I know he was really unprepared for the movie. He was really excited when he saw the film. It really felt good."

Guardians of the Galaxy is in theaters now, so you can judge Brolin as Thanos for yourself all weekend long.

(via CBM)