Troian Bellisario (born Troian Avery Bellisario) is an American actress.
She is the daughter of Donald Bellisario and Deborah Pratt. She is the half-sister of Michael Bellisario and stepsister to Sean Murray. ellisario guest starred alongside her stepbrother, Sean Murray, on the televison series NCIS. In November 2009, Bellisario was cast as Spencer Hastings in the TV series Pretty Little Liars based on the book series by Sara Shepard.