DC Universe's upcoming Swamp Thing live-action series has found its Alec Holland and his monstrous alter ego.

Andy Bean, who will appear as adult Stanley in It: Chapter Two, has been cast as biologist Alec Holland, whose discovers a bizarre illness afflicting a small town may be connected to his work in the swamp. That revelation places him in conflict with dark, supernatural forces, from which he emerges as the elemental Swamp Thing.

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That role will be portrayed by Derek Mears, whose credits include Sleepy Hollow, Marvel's Agents of S.H.I.E.L.D., Live by Night and Friday the 13th. Mears' involvement was first reported in September, but this is the first official confirmation.

Bean and Mears join a rapidly expanding cast that includes Crystal Reed as Abby Arcane, Maria Sten as Liz Tremayne, Jennifer Beals as Lucilla Cable, Jeryl Prescott as Madame Xanadu, Virginia Madsen as Maria Sunderland, and Will Patton as Andy Sunderland.

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Based on the DC comics series, Swamp Thing follows Abby Arcane (Reed) as she investigates what seems to be a deadly swamp-born virus in a small town in Louisiana. However, she soon discovers the swamp holds mystical and terrifying secrets.

Executive produced by James Wan, Mark Verheiden, Gary Dauberman, Michael Clear and Len Wiseman, Swamp Thing will premiere in 2019 on the DC Universe streaming service.