Mark Hamill

There'll be a force to be reckoned with on Criminal Minds next month: Star Wars alum Mark Hamill will guest-star in the drama's two-part season finale, TVGuide.com has learned exclusively.

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Details about Hamill's role are being kept under wraps, but could he be the BAU's season-long unsub/stalker The Replicator? In the two-hour episode, the team's pursuit of The Replicator will come to a head when one of them becomes a victim. Executive producer Erica Messer

also previously told TVGuide.com that the BAU won't come face-to-face with The Replicator until the season's final two episodes.

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In addition to playing the galaxy's top Jedi Luke Skywalker, Hamill is also known for his voice work on Robot Chicken The Cleveland Show and, most notably, as the Joker in several animated Batman series. Other TV credits include guest spots on Chuck 's final season and on The Neighbors ' season finale two weeks ago. Hamill is also in talks to return for the new Star Wars films.Criminal Minds' two-part Season 8 finale will air Wednesday, May 22 at 9/8c on CBS.(Full disclosure: TVGuide.com is owned by a joint venture between Lionsgate and CBS.)