A Once Upon a Time fan favorite is heading to NBC's Law & Order: SVU.

Eion Bailey will guest star on NBC's Law & Order: SVU, The Hollywood Reporter has learned exclusively.

The actor will play Frank Patterson, a veteran of the Iraq war with PTSD who is a key witness in an investigation of a sexual assault in a nightclub. He'll appear in episode 21 of the series, slated to air in April.

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The casting comes days after Bailey's Once Upon a Time character August transformed into Pinocchio for the first time on the ABC drama.

In addition to Once, Bailey's small-screen credits include Covert Affairs, ER and a 2011 episode of Law & Order: Criminal Intent. He's repped by Gersh and the Susan Smith Co.

Law & Order: SVU airs Wednesdays at 9 p.m. on NBC.

Email: Lesley.Goldberg@thr.com; Twitter: @Snoodit