It seems that the best job an actor can get these days is on a Marvel or DC film, but some actors aren't the pickiest of people when it comes to taking a role. For most, it has to be something that interests them, and there isn't a lot out there that's more interesting than playing a superhero or supervillain. Granted, the Academy of Motion Picture Arts and Sciences doesn't necessarily agree, but that hardly matters when you see how many big stars have strapped on some tights and added their names to the likes of the Justice League and the Avengers.
Landing one acting gig for Marvel doesn't make it easy to snag one for DC, but there have been several actors and actresses who've jumped from one universe to another, playing characters in both a Marvel and a DC film. Most don't get the chance, but these performers have appeared in at least one Marvel and one DC film.