Jamie Campbell Bower played Caius in the Twilight movies. Then he played the young Gillert Grindelwald in the two Harry Potter and the Deathly Hallows movies. And he followed that up by playing Jace in The Mortal Instruments movies. Three book series turned into movies and he's in at least two movies from each franchise (including the 2nd Mortal Instruments movie, since it's been officially announced).

 

I just figured this out.