Although James Earl Jones is well known as the voice of Darth Vader, it was David Prowse who was the one inside the Sith Lord’s armor during the original Star Wars movies. Even if you’ve never seen Prowse outside of the Darth Vader suit, it’s already clear he’s an imposing man. So when in the weeks leading up to Superman: The Movie, director Richard Donner called Prowse and asked him to help train Christopher Reeve and get him into proper Superman shape. A New Hope hadn’t been released by that point, but Donner knew that Prowse was a bodybuilder and weight-training instructor, so he was the right man for this particular job. As you can tell by the above comment unearthed by THR, Prowse ultimately succeeded in helping Reeve put on the weight, thus allowing him to play a physically-fitting version of Superman. When combined with Reeve’s natural charm, it’s no wonder why his iteration of the Kryptonian hero is still so popular.