The Harry Potter actor will take on the role of fallen god Hephaestus in the follow-up to last year's fantasy epic.
Rumoured stars Toby Kebbell (Argenor) and Rosamund Pike (Andromeda) have also been confirmed for roles in the blockbuster, titled Wrath Of The Titans.
Sam Worthington will reprise his role as Perseus, while returning stars Liam Neeson, Ralph Fiennes and Danny Huston will be joined by franchise newcomer Edgar Ramirez (Carlos).
Battle: Los Angeles director Jonathan Liebesman is behind the camera for Wrath Of The Titans, which will film at Shepperton Studios and on location in Surrey, South Wales and Tenerife.
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