Gail O'Grady, Nathan Fillion

NYPD Blue vet Gail O'Grady is back on the beat — sort of. The Emmy nominated actress will guest-star on an upcoming episode of Castle, TVGuide.com has learned exclusively.

O'Grady will play Margo Cowan, one of the stars of the hit Real Housewives-esque reality show The Wives of Wall Street. The cameras follow her as she runs her cosmetics empire — an empire that employed the victim of a murder the team is investigating.

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O'Grady joins Gina Torres, who will play one of Cowan's Wives of Wall Street co-stars, as first reported by TVLine. Their episode, titled "Reality Star Struck," is set to air in February.

Aside from playing Blue's big-haired squad secretary Donna for three years, O'Grady is also known for her role as American Dreams' family matriarch. She most recently guest-starred on Hawaii Five-0 last year.

Castle airs Mondays at 10/9c on ABC.