Source: comicsbeat.com

2. Ocean Master

Oh, thank God, we get to talk about the villains people actually know now. I don't have to struggle to reach my word limit.

Ocean Master is like DC's Loki, only he's not as cool and no one wants to f**k him. Orm Curry's origin was retconned multiple times, so here we go with the explanation. First, he was fully human instead of half human like Aquaman. Then he was fully Atlantean, and Aquaman was too. Then Aquaman was half Atlantean again, but Orm was fully Atlantean this time. It's a whole thing.

Regardless, Orm has always been Aquaman's angry usurper brother who wants the throne of Atlantis, and he’ll murder his bro to get that done. Like I said, Water Loki. He only really fights Aquaman, which makes sense. When your name is Ocean Master, you aren't gonna make much of a career in Gotham.

Why he isn't more popular: I honestly don't know. His visual design is sub-optimal, but he's just Aquatic Loki, and people love Loki.