Peter MacNicol has joined the cast of Grey's Anatomy for a multi-episode arc, has learned exclusively.

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MacNicol, who starred in Ally McBeal, Numb3rs and 24, will play Dr. Stark, a pediatrics attending who will be working closely with Alex (Justin Chambers).

The 56-year-old actor will pop in during sweeps for at least two episodes.

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Grey's Anatomy airs Thursdays at 9/8c on ABC.