Who she is: Mera, Queen Of Atlantis
Her power: Unknown, but traditionally comparable with the powers of Aquaman. She can breathe under water, has super strength and basic telepathy, and can manipulate water into various shapes and densities.
Her story: Mera has yet to make her first appearance, but in the comics she’s traditionally a native of an aquatic dimension called Xebel (or Dimension Aqua). When a villain took over her kingdom, Mera escaped to Earth and met Aquaman, with the two of them eventually getting married. It’s unclear if any of that will be retained for the movies, though.
Played by: Amber Heard
Currently, Mera is: Dramatically standing on some rocks, waiting to be introduced.