It doesn't just rain unexpected comic book movie casting news, it pours. According to THR, 1980s action legend Dolph Lundgren is the latest star to sign on to play a character in James Wan's upcoming Aquaman stand-alone. He is set to play King Nereus, a relatively new addition to Aquaman comic lore, who only debuted in 2013.
So far, the character has only appeared in five issues of Aquaman and seven issues of DC's Bomshells, so there's not a great deal of story to go on with him. He's the leader of the Xebels, the group of exiled Atlanteans that Mera was once a member of and a one-time ally of Orm the Ocean Master in his quest for power.
THR's description of Nereus reads as follows: "Lundgren will play King Nereus of the aquatic kingdom of Xebel, who claims Mera as his own and wants to kill Aquaman." That's an interesting, pretty classical take on the character, and it wouldn't be a great surprise if he ends up aligning with the Ocean Master (played by Patrick Wilson).
Inevitably, the knee-jerk reaction of any comic book movie having three villains (or Spider-Man Sequelitis to give it its medical name) is to gnash your teeth wildly and proclaim it an inevitable mess, but there's really no telling how much of a role Nereus is even going to play. No offence to Lundgren, but it's supremely unlikely that he's going to have as much screen-time as either Wilson or Yahya Abdul-Mateen II as Black Manta.
Plus, James Wan says he's not even a full bad guy (which makes the "wants to kill Aquaman" comment a little odd)...