Actors are known to change up their look for new roles, and some of them do it more intensely than others. You can get jacked up or get a perm or even CGI genitals, if that is what the movie requires.

For Oppenheimer, Josh Hartnett admitted that he gained 30 pounds for the role, which is not unheard of in Hollywood. But his co-star Matt Damon seemed to give him a hard time about it. “He gave me a lot of good advice. One in particular — one thing that was just so unhelpful: he told me not to gain the weight I’d already gained for the role,” Hartnett told Jimmy Fallon this week on The Tonight Show.