Arnold Vosloo

Sherlock Holmes is going to be very busy in the Elementary finale.

Arnold Vosloo has been tapped to guest-star as an adversary for Holmes in the May 16 season-ender, TVGuide.com has learned exclusively.

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Vosloo, best-known for playing villain Imhotep in The Mummy, will portray Christos Theophilus, a Greek shipping magnate with a criminal past whom Sherlock (Jonny Lee Miller) believes is in league with the mysterious Moriarty. As we teased in our must-watch finales gallery, Moriarty will play a major role in the two-hour season finale when it's revealed that he may be operating in New York.

Elementary executive producer Rob Doherty also told TVGuide.com that another lieutenant in Moriarty's employ would unlock some shocking revelations. In this case, Holmes will uncover a frightening personal motivation that ensures Christos will stop at nothing to carry out Moriarty's plan. Translation: Be afraid. Be very afraid.

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Vosloo, whose television credits include Bones, 24 and NCIS, will make his debut in the two-hour finale, which will also feature Game of Thrones' Natalie Dormer. As TVGuide.com first reported, Dormer will play Sherlock's true love Irene Adler.

Elementary returns this Thursday at 10/9c on CBS and will air original episodes through sweeps.