The Cowboys & Aliens actor, who recently married actress Rachel Weisz, said that he thinks there is other "life out there".
"I do believe there's life out there. I'm not sure I believe they've been to Earth but there is life out there," he explained.
Craig recently revealed that it was "a joy" to star in a film opposite screen legend Harrison Ford and play a cowboy in Cowboys & Aliens.
"I wanted to be a cowboy more than I want to be anything else. I had a plastic Winchester toy gun which was free at a fair," he commented.
"It's been a joy, I've been lucky and doing it with Harrison Ford, too, so two for one."
Watch the trailer for Cowboys & Aliens below: