Why Don’t Marvel Actors Cross Into DC — Contract Clause or Unwritten Rule?

Studios stay quiet, but fans keep asking the question.
Every time a Marvel star dazzles on screen, fans inevitably wonder: could they one day swap sides and appear in a DC film? The idea sounds simple, but the reality is more complicated.
While actors often sign multi-picture deals with Marvel Studios, there is no publicly known clause in those contracts that explicitly bans them from appearing in DC projects.
What Marvel and the Actors Say
Kevin Feige, Marvel’s president, has admitted that contracts have changed over the years, moving away from strict, decade-long commitments. Yet actors themselves sometimes joke about being 'locked in.'
Chris Hemsworth even quipped it was "illegal" for him to join DC — though in a tongue-in-cheek way. It’s fair to say that while no written ban has been confirmed, there’s a strong expectation of loyalty while an actor is active in the MCU.
The Reality Behind the Myth
Why don’t we see Marvel stars moonlighting in Gotham or Metropolis? TThe answer is likely practical. MCU schedules are demanding, leaving little room for actors to juggle major roles elsewhere. And studios hardly want to market someone as a Marvel hero while they also show up as a DC icon.
So is it a clause, an unspoken rule, or just good old-fashioned Hollywood etiquette? The studios aren’t saying, and perhaps that’s part of the fun — the speculation keeps both fandoms buzzing.