DC Comics Super Heroes Aquaman
Aquaman's been a major player in DC Comics since the 1940's, and has been a part of nearly every version of the Justice League. He's gone through a lot of changes over the years, including losing an arm, getting all beardy and scraggly, and being used for over-the-top comic relief in the recent Batman: The Brave and the Bold cartoon. Adults know him, kids know him.
The version of Aquaman I propose is the most colorful, in my opinion most kid-friendly version, and the version that's the most classic--the simple orange-shirted, yellow-belted, green-gloved King of the Seven Seas. Give him a trident and some fishy friends, and you've got your hero. No new pieces would be needed for this minifigure--he could easily be made from existing parts.
Black Manta's archenemy is Black Manta; a founding member of the Legion of Doom, and a great associate for Lex Luthor, the Joker, and other supervillains. My version (above) uses existing pieces, but an all-new helmet design that's more accurate to the character would be great too. He'd make a great LEGO villain along the lines of OGEL and other classics.
Aquaman had other villains as well; his brother became Ocean Master, another villain who tries to take over Atlantis from time to time, and the Fisherman, a surface dweller who comes to attack. Aquaman has also been a longtime crusader for protecting the oceans from pollution and other environmental attacks, so that angle could work too.
Aquaman has many friends and family members--his wife Mera would be a nice female superhero addition to the lineup, and could actually re-use Wonder Woman's tiara hairpiece now that that's available. There have been a few different Aqualads--the one pictured above is the classic "Silver Age" Aqualad, Garth; but the new one as seen on Young Justice would be nice as well.
Like Batman, Aquaman had a cave headquarters, called the "Aquacave." It was filled with his treasures and trophies from a life of crimefighting, and was a place where he could research and plan heroic adventures. While I think LEGO's chances of making something along the lines of the Aquacave are farfetched, I think this demonstrates that LEGO has a lot of these pieces already made, and the various sharks, rays, octopi, and other sea creatures would make great allies for Aquaman and his friends.
Ideally, I'd like to see:
Aquaman included with the other DC Comics Super Heroes--it could be alongside them in playsets (as Wonder Woman was included in the Superman vs. Lex Luthor set) or in his own sets independent of other heroes:
AQUAMAN SEA SCOOTER ($11.99)
Includes Aquaman, Sea Scooter (as seen on Super Friends and other programs), small boat with distressed passenger.
AQUAMAN UNDERWATER PATROL ($24.99)
Includes Aquaman and Aqualad on patrol riding giant seahorses (either moulded ala Tauntauns or brick-built ala Atlantis), an Aquaman villain like Ocean Master or the Fisherman.
AQUAMAN BLACK MANTA'S ATTACK (34.99)
Includes Aquaman, Mera, Black Manta, a Manta Henchman, and a small version of Black Manta's Mantaship, with a "broken" section of Atlantis where Manta has attacked.