Andy’s answer to “Matt Damon has been cast to play Mark Watney in the upcoming movie adaptation of your book. If you …” > Likes and Comments

Nail on the head with Bradley Cooper. He'd have also been great.
Thinking out of the box - Ryan Gosling or Joseph Gordon-Levitt might've been interesting choices, too.

Ooh, I never thought of Bradley Cooper doing it, because I was so happy it was Matt Damon, but Cooper does have that cheeky smart-ass thing going for him, too… interesting to think of him playing Mark...