Thanos is largely expected to be one of the main villains in the upcoming Avengers movie, although he’d probably refer to himself as the hero of his own story. Thanos happens to be the best constructed bad guy in Avengers history so far, so Marvel will want to continue to put the character to good use in Avengers: Endgame. But there may be an even more significant threat looming. A new fan theory has already identified the kind of villain that would get the job done, and it’s a villain from the MCU that we already saw in a previous movie.

We saw a theory a few days ago that said the Thanos of the past would be the villain of the film. It’s almost the same Thanos, with the same agenda. At the same time, he’d be an anti-hero who has no Infinity Stones. That theory said the surviving Avengers would battle Thanos in the past to prevent him from collecting the stones and killing half the universe. That Thanos and his colossal army would be a formidable threat, as the Battle of New York has shown.

A new story, however, says that a different villain might take advantage of what had just happened to the world in the present. Because Doctor Strange passed away, for the time being, and can no longer enforce his pact with Dormammu, it’s Dormammu who might prove to be the bigger threat for the remaining universe.

Given that he’s a villain who wants Earth for himself, it’s likely that the creature hasn’t given up on his plans of conquering the planet, Reddit user ak2sup believes. And with Doctor Strange temporarily unable to stop him, Dormammu might swoop in. Just because Thanos killed half of the living creatures in the known universe, doesn’t mean all the other villains have stopped plotting their own nefarious schemes.

And Dormammu happens to be the big villain we already know from the MCU, a character that wasn’t explored enough in Doctor Strange. This Marvel fan argues that rather than introducing a new villain, like The Living Tribunal, Eternity, or Galactus, Marvel would be better off using Dormammu.

The Reddit user also points out there may be one other clever hint that Dormammu is a villain in Endgame. There’s no new major addition to the film’s cast who would play or voice a new villain. Benedict Cumberbatch, whose Doctor Strange died in Infinity War, will appear in Endgame. But the British actor also happens to have voiced Dormammu in the first Doctor Strange movie, and he may do the same thing in Endgame.

Like always, this is just a fan theory so we’ll have to wait until April 26th to see what Marvel has planned for the new Avengers movie. The full fan theory, meanwhile, follows below.