Showtime's Halo is rounding out its cast as it prepares to begin filming this fall. The network announced six new cast members, including Designated Survivor alum Natascha McElhone, at the Television Critics Association summer press tour on Friday, as well as the news that the series is set to premiere in the first quarter of 2021.

Joining American Gods' Pablo Schneider as the video game's faceless hero Master Chief and Yerin Ha as new character Kwan Ha, a 16-year-old from the Outer Colonies who has a fateful meeting with Master Chief, are McElhone, Emmy nominee Bokeem Woodbine, Shabana Azmi, Bentley Kalu, Natasha Culzac, and Kate Kennedy. The latter three will be playing new characters in the Halo universe created for the series.

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Here's the breakdown of all the characters.

Dr. Catherine Halsey (McElhone) - The "conflicted and inscrutable" creator of the Spartan supersoldiers.

Cortana (also McElhone) - The most advanced A.I. in history and potentially the key to saving human existence.

Soren-066 (Woodbine) - An old friend of Master Chief who has become a privateer on the edge of civilization. He'll be brought back into the conflict to go up against his former military masters and Master Chief, as well.

Admiral Margaret Parangosky (Azmi) - The head of the Office of Naval Investigation.

Spartan Vannak-134 (Kalu) - A cybernetically augmented supersoldier created at childhood who serves as deputy to Master Chief.

Spartan Riz-028 (Culzac) - A cybernetically enhanced killer.

Spartan Kai-125 (Kennedy) - Another Spartan supersoldier.

Halo is set to premiere in the first quarter of 2021.

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<p>Natascha McElhone, Designated Survivor </p>

Natascha McElhone, Designated Survivor