Namor is Marvel Comics' oldest character, but unlike Superman or Batman,
he has never been a pure hero who fought for what's best for us. He has
often switched sides, both helping us against the Nazi's, and fighting
against us when we polluted his underwater kingdom with waste.
Between the Golden Age and the Marvel Age, Namor was missing until
Fantastic Four #4 where he was rediscovered, ironically, by the later
version of the Human Torch. Namor between those eras had amnesia, and
it wasn't until the Torch shaved off Namor's beard and threw him into
the water, that he regained his memory. However, upon seeing the
polluted wreckage that humanity had caused his underwater kingdom to
become, Namor turned into one of Marvel's most feared villains. Today
Namor has once again become a hero (more or less). He has even joined
the ranks of the superhero team The Avengers for a short while.
Namor first appeared in a give-away comic called Motion Pictures Comic Weekly. This 8 page story about him was later expanded and re-printed in Marvel Comics #1. Namor has become a central impetus to some of Marvel Comics biggest happenings, particularly the revival of Captain America in the 1963 and another character known as Iron Fist in the 1991.
Click here to see a big Namor Gif