First appearance: Marvel Mystery Comics #82
As with many of the other characters of the era, Namora began her career as the gender-swapped version of an already-established character - in this case, Namor the Sub-Mariner. She mostly appeared in other characters’ comics, and was typically relegated to a supporting role - save for a short, three-issue run in her own series.
What makes Namora stand apart from other, similar heroes was her standing amongst her male counterparts. Time and time again, the comics have shown that Namora was (and still is) equal in power to her more popular cousin. Even when the character first debuted in 1947, it was clear that Namora wasn’t simply a weaker, female version of a hero that already existed - Marvel Comics quickly cemented the fact that Namor and Namora were 100% equals in terms of power.
Sadly, Namora’s presence in Marvel’s ongoing series has dwindled over the past several years. With characters like Namor losing steam, it only makes sense that the supporting cast would fall by the wayside as well. At the very least, when Namora does appear, the writers do a fine job of keeping her strong personality intact - but at this point, it doesn't seem like the Atlantean will be making many big appearances any time soon.