Shabana Azmi (“The Reluctant Fundamentalist”), Bentley Kalu (“Avengers: Age of Ultron”), Natasha Culzac (“The Witcher”) and Kate Kennedy (“Catastrophe”) have also been cast in the series.

“Halo” has sold more than 77 million copies worldwide and grossed over US$60 billion in lifetime sales.

The Showtime adaptation will focus on an epic 26th-century conflict between humanity and an alien threat known as the Covenant.

McElhone will play two characters: Dr Catherine Halsey, the brilliant, conflicted creator of the Spartan supersoldiers, and Cortana, the most advanced AI in human history, who may hold the key to the survival of the human race.

Woodbine plays Soren-066, a morally complex mercenary who finds himself up against his former military masters and his old friend, the Master Chief.

Azmi will play Admiral Margaret Parangosky, the head of the Office of Naval Intelligence.

The series will also introduce three new characters to the “Halo” universe.

British actor Kalu plays Spartan Vannak-134, a cybernetically augmented supersoldier, who serves as deputy to the Master Chief.

Culzac plays Spartan Riz-028, a deadly killing machine. Kennedy stars as Spartan Kai-125, a curious, courageous – but equally deadly – supersoldier.

They join previously announced series lead Pablo Schreiber, who will play the Master Chief, and Yerin Ha, who is playing a new character named Kwan Ha, a clever, audacious 16-year-old from the Outer Colonies.

Kyle Killen and Steve Kane will serve as co-showrunners and executive producers. The series is produced by Showtime in partnership with 343 Industries and Steven Spielberg’s Amblin Television. It is set to air in the first quarter of 2021.