Courtesy of HBO

The cast of HBO’s “Watchmen” pilot continues to grow.

Yahya Abdul-Mateen II and Sara Vickers have both joined the project, which hails from Damon Lindelof. As with previous “Watchmen” casting announcements, HBO provided no details about the characters the two will play.

They join previously announced cast members Regina King, Don Johnson, Jeremy Irons, Tim Blake Nelson, Louis Gossett Jr., Adelaide Clemens, Andrew Howard, Tom Mison, Frances Fisher, and Jacob Ming-Trent.

This project marks the second superhero property in which Abdul-Mateen will appear. He is also set to appear as Black Manta in the upcoming “Aquaman” film opposite Jason Momoa. The actor is also known for his appearance as the disco-loving gangster Cadillac in the Netflix series “The Get Down” and was recently featured in “The Handmaid’s Tale.” On the film side, he played Sgt. Ellerbee in the recent “Baywatch” movie and had a role in the Oscar-nominated film “The Greatest Showman.”

He is repped by Gersh and Anonymous Content.

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Vickers is best known for her role as Joan Thursday in ITV’s Inspector Morse prequel, “Endeavour.” Her other TV credits include “The Alienist,” “The Crown,” “Man Down,” “Bert & Dickie,” and “Privates.” She has also been featured in the films “Sunshine on Leith,” “Breaking,” “Thought for a Day,” and “Connect.”

She is repped by Curtis Brown Group.

Lindelof previously posted a letter to fans in which he laid out his vision for the series, which he said will not be a re-telling of the story from the original graphic novel, but rather a new story in the same world with new characters set in the present day. The original story followed a group of crimefighters investigating the murder of one of their own. In the process, those characters — including Doctor Manhattan, Nite Owl, Silk Spectre, and Rorschach — uncover a conspiracy with enormous implications. It is unclear which, if any, of those characters will appear in Lindelof’s version.

“Some of the characters will be unknown,” Lindelof wrote. “New faces. New masks to cover them. We also intend to revisit the past century of Costumed Adventuring through a surprising yet familiar set of eyes…and it is here we will be taking our greatest risks.”

Lindelof will write and executive produce. Nicole Kassell will direct and executive produce. “Watchmen” is produced for HBO by White Rabbit in association with Warner Bros. Television.