Namor: the Sub-Mariner is one of Marvel’s oldest properties debuting in April 1939. However, his film rights have been with Universal. There have been a couple of rumors about a planned film, but they keep falling apart.
But now, according to Marvel Chief Creative Officer Joe Quesada, the Namor rights have reverted to Marvel, meaning he can finally join the Marvel Cinematic Universe. In my opinion, Namor is cooler than Aquaman, maybe they’ll include him in future plans.