John Lithgow to Play Neil Patrick Harris' Dad on 'How I Met Your Mother'

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It's official: John Lithgow will play Barney Stinson's (Neil Patrick Harris) dad on How I Met Your Mother, co-star Cobie Smulders confirms.

Smulders, who plays Robin in the CBS sitcom, joked on TV Guide Network's Hollywood 411 that she was terrified of Lithgow after his turn as a serial killer on Dexter.

Still, she says "it's really exciting and different for our show. He's such a pioneer."

CBS confirms the episode will air around the end of February.