When an actor is cast in a comic-book movie without any mention of who he's playing, it's usually because it's someone that fans will know. That was the case with Evan Jonigkeit, who joined "X-Men: Days of Future Past" in an unspecified role. But at the premiere of "Girls," which stars his girlfriend Zosia Mamet, he revealed to MTV News which familiar mutant he's bringing back to the big screen.

Jonigkeit is playing a younger version of Toad, a character that hasn't been seen since the original "X-Men" movie in 2000, when Ray Park played him. Reintroducing Toad is a significant step toward setting up the events of that original movie and may suggest that the Michael Fassbender's Magneto will establish the Brotherhood of Evil Mutants in the upcoming "First Class" sequel.

A comic-book fan himself, Jonigkeit shared his enthusiasm about becoming a part of the X-Men universe, especially as a character who has been around since the very early days of the superhero team. "It's a really incredible thing to be a part of," he said. "['Days of Future Past'] is huge and really exciting. I was so stoked to be working with all of these people. It was a really crazy experience."

Though it has been such a long time since Toad appeared in the film, Jonigkeit's version of the character does work in harmony with Park's portrayal. He explained how his Toad sets up the one from "X-Men" and how he prepared for the role. "I read a lot of the comic books. I found out the storyline of my character, who is Toad," he said. "X-Men fans will know that Ray Park played him in the first movie, so it's a generation story of how he came to be. It's really cool."

But don't expect a Toad that looks exactly like the evil mutant he'll grow up to be. Jonigkeit teased that the character's look had changed significantly, but he wouldn't revealed exactly how. "The aesthetics of the character are much different, and I'm not really allowed to say a whole lot more than that," he said. "It's darker. I would say it's a darker tone."

"X-Men: Days of Future Past" opens in theaters on May 23.