Source: comicbookmovie.com

5. King Shark

Nanaue!!!!! I love this dude.

He is the son of something called the King of All Sharks, which is the comic book-iest thing ever, and I love it with all of my flippin' heart. He's also from Hawaii, which…uh…screw you, King Shark. I've been to Hawaii. It's beautiful. Go enjoy that instead of wasting your time on shark crime. Also, calling yourself King Shark when your father is the King of All Sharks is just confusing. Don't mess with the branding, bro.

King Shark fought Superboy a whole bunch, and even got himself assigned to an iteration of the Suicide Squad, and even joined the Secret Six in his best-ever role. And he fought Aquaman or whatever; that's not as important as Secret Six being great as hell. In his latest appearance, King Shark faced off with the Teen Titans under the Black Manta’s orders. That's right, Shark, working with a better Aquaman villain will bump up your profile.

Why he isn't more popular: Not enough people have read Secret Six.