Alexandra “Alex” Drake is a fictional character created by I. Marlene King and portrayed by Troian Bellisario in the American television series Pretty Little Liars. Officially introduced in the series finale, Alex Drake is both the identical twin of main character Spencer Hastings and the previously anonymous identity known as "A.D." In childhood, Drake was adopted by a wealthy British family that later abandoned her, forcing Alex to bounce around foster homes and orphanages. Because of this, Alex would frequently impersonate Spencer in adulthood due to jealousy over her happier upbringing.