For those who may not know, Namor is one of the oldest comic book heroes. Created in the 1930s, Namor is a prince from Atlantis who is half mutant half Atlantean. He has served as both a hero and an anti-hero while working with the X-Men and the Avengers. Below water, he uses powers that are usually associated with those that live in Atlantis (control of the seas, communication with sea life, rapid swimming, super strength) while above the water he can fly and fight well enough to battle with the Avengers' enemies. His history is convoluted, but Namor may be heading to the Marvel Cinematic Universe soon.
Marvel Studios head Kevin Feige commented on Namor joining the MCU back in 2018, stating, "I think there’s a way to probably figure it out but it does have — it’s not as a clean or clear as the majority of the other characters." Namor's distribution rights belong to Universal, much like The Hulk. The second Hulk film (which is included in the MCU timeline) may be owned by Marvel, but it was distributed by Universal. Mark Ruffalo once stated that there wouldn't be another solo Hulk film because Universal doesn't "know how to play well with Marvel." So while Namor, like Hulk, may be difficult to fit into a solo film, he can still be included in a broader Avengers film (much like Hulk in Thor: Ragnarok)
Doctor Strange 2 director Scott Derrickson tweeted then deleted an image from the 2011 comic book series Fear Itself: The Deep, which showed Strange and Namor swimming together. The post was captioned “Are You Experienced?,” which references the famous Jimi Hendrix song where the lyrics speak of watching the sunrise “from the bottom of the sea." Soon after that tweet was deleted We Got This Covered claimed that a source close to the situation says Namor is expected to cameo in either Black Panther 2 or Doctor Strange 2. Namor and Black Panther aren't friendly, and Namor once flooded Wakanda and killed millions in an attempt to anger the Avengers due to a beef with the X-Men. We'll have to wait and see how this one turns out.