Getting the look of a superhero (or villain) is no easy feat.

In comic books, artists can draw up herculean proportions that make mere men look like dominant, invincible gods.

But when an actor has to do it for real—that takes major work.

After all, if you’re going to pummel bad guys with super powers or scale tall buildings in a single bound, you have to look the part.

Here’s how 13 Hollywood stars transformed their physiques to do just that.