The Black Manta character has been strongly rumored to appear in Aquaman since the summer of 2016.
For those less familiar, Black Manta has been around in the world of DC Comics since the late 1960s and typically is presented with a more sympathetic backstory.
However, Wan has long been careful to downplay those same rumors – without outright denying that there is any truth to them, at the same time.
Seeing as Ocean Master is also a part of Wan’s DCEU film, it’s plausible that the former will serve as the movie’s primary antagonist – with Black Manta being introduced and set-up to become the main villain in a future Aquaman big screen adventure, instead.