Mr. Fantastic - Reed Richards
A fan-favorite casting if there ever was one. MCU and The Office fans have been wanting to see John become a superhero since the casting rumors came out about him having auditioned for the role of Steve Rogers (Captain America) over a decade ago. Fans were clamoring, even more, for
John after he beefed up for a role in 13 hours. He also plays a hyper-intelligent character in Jack Ryan on Amazon.
Krasinki would bring great balance to the role. John can play the smartest guy in the room while not making you hate him, and he's shown that he can take on action roles while obviously having the chops in incorporate MCU's classic witty banter.
Howerton has better acting chops than he is given credit for. Howerton plays the cocky Harvard professor on AP BIO, and is known for his role as Dennis on It's Always Sunny in Philadelphia. Howerton could play the character in a way that is a mix of both Dr. Strange and Tony Stark. In many ways, Stark started out as unlikable but fun, and Strange was pompous until humbled.
Howerton could balance out those aspects of the character while also coming across as not too nerdy to be a hero but also shows that he's the genius that puts in the time. His work isn't effortless in the way Stark's is... he's a genius, but it requires time and energy and it's worn him out.
Howerton was in the running to play Peter Quill/Star-Lord in Guardians of the Galaxy... so he's already on Marvel's radar!
Best known for his role as Jeff Winger, the egomaniac with a heart of gold on Community, where
the Russo brother's unknowingly auditioned for their MCU directorial debut when shooting the show's "Modern Warfare" episode.
McHale can be an acquired taste, but his ability for quick, witty, believable banter and is something that the MCU will need. He excels when surrounded by the right cast of misfits and the MCU's F4 can be that team for him. He's even got some superhero experience working on the CW's Stargirl now.
However, if he did get cast, don't tell Jeff Winger who openly dislikes Marvel movies.
After watching Netflix's You with my wife, I thought Badgley has what it takes to play Reed Richards.
He is intelligent and sophisticated. He's dark and mysterious. He can play it light and romantic and can even be humorous. This would take the character in a younger direction, but I think he can pull it off!