In today's What If...? finale, it's revealed that The Watcher has intervened in many realities and saved Variants of Steve Rogers, Riri Williams, and Reed Richards.
We've already met one alternate version of Mister Fantastic in the MCU; in 2022's Doctor Strange in the Multiverse of Madness, John Krasinski played a Reed who had joined Earth-838's Illuminati. However, his time in the role was short-lived after the Scarlet Witch popped his head like a balloon.
Pedro Pascal will play the MCU's main Mister Fantastic in The Fantastic Four: First Steps but it sounds like he'll have some company in Avengers: Doomsday and Avengers: Secret Wars.
According to The Cosmic Circus' Alex Perez, there may be plans in place for Fantastic Four and Fantastic Four: Rise of the Silver Surfer star Ioan Gruffudd to reprise the role of Reed. He'd later hint that the Variants left stranded in The Void will be key to the return of familiar faces, something that makes sense when the prevailing theory is that it essentially becomes "Battleworld."
The scooper also reiterated past claims that we'll see the Council of Reeds assemble in the next Avengers movies. That makes sense with Doctor Doom set to serve the role of the MCU's new big bad, of course.
In the comics, the Interdimensional Council of Reeds is an organization composed of multiversal counterparts of Reed Richards, specifically those who developed interdimensional portal tech called the Bridge. They gathered together to "solve everything," but members had to leave their families to join.
The Council was founded by a trio of Infinity Gauntlet–wielding Reeds: Reed-12498, Reed-98570, and Reed-99107.
"I would love that," Gruffudd said of a possible MCU role in 2018. "I just don't know, in that universe, the Marvel world, would they let me play something else? I'm so renowned for Fantastic Four. But a couple of actors have [made the leap]."
"I'm sure for Marvel it was a tough decision to pick Chris to play that part [Captain America] because he'd already played one superhero, but what a brilliant decision it was, because he's wonderful," the Welsh actor continued. "And Michael B Jordan has played Johnny Storm and he's amazing in Black Panther as well, so there are precedents set. So we'll see."
"Maybe [I could play] a baddie, this time? Now that I've established myself as somebody who can do that, that would be great."
A villainous Mister Fantastic might fit the bill...