Aquaman: Return of the King was the eighteenth installment of the DC Cinematic Universe, and the second film in Phase Three. The film was directed by James Cameron and was written by Cameron, Geoff Johns and Christopher Yost. Aquaman: Return of the King serves as a sequel to both Aquaman and Aquaman: The Trench.
- Sam Claffin as Arthur Curry/Aquaman
- Sylvester Stallone as Atlan/The Dead King
- Emilia Clarke as Mera
- Drew Roy as Garth
- Corey Hawkins as Jackson Hyde
- Wes Bentley as Orm Marius/Ocean Master
- Danny Devito as Nuidis Vulko
- Jimmy Smits as Tom Curry
- Damian Lewis as Nereus
- Frank Welker as Creatures from the Trench (voice only)
- Harrison Ford as Orin (flashback only)
- Kim Basinger as Queen Atlanna (flashback only)
- Billy Zane as Lex Luthor (flashback only)
- Matt Bomer as Hank Henshaw (flashback only)
After the events of Justice League: The Savage Time, Aquaman returns to the city of Atlantis, more powerful than ever. The original king of Atlantis, Atlan, awakens and contacts Aquaman using telepathy, claiming he is mistaken to think that he was king of Atlantis. After the Dead King reveals to the entire city of Atlantis that his brother Orin, the one who killed him, was a descendant of Aquaman, he begins to build an army of his followers. With the Trench, Nereus and his people of the Xebel colony, and Ocean Master on his side, the Dead King starts a war between himself and Atlantis, led by Aquaman. Alongside his friends and family, Aquaman is forced to go to war, in order to remain on the throne.
Lex Luthor walks into a warehouse owned by LexCorp, where he is shown to be keeping all of his weaponry used against Superman in Superman: Man of Metropolis. Inside waiting for him is Hank Henshaw, a crew member from the NASA space shuttle that was struck by a solar flare during the events of Justice League. Henshaw's body is decaying following the solar flare that hit him and his crew, and as Henshaw explains to Luthor, he needs help to continue to live. Luthor agrees to save Henshaw, but under one condition; Henshaw will repay him when Luthor calls. Henshaw agrees immediately. Luthor asks Henshaw, "How do you feel about cyborgs?", before the screen fades to black.