Question: who is alex drake in pretty little liars

title: Alex Drake (Pretty Little Liars)
text: Alex Drake is a fictional character created by I. Marlene King and portrayed by Troian Bellisario on the American television series Pretty Little Liars . She was officially introduced in the episode `` Till Death Do Us Part '' , revealed to be Spencer Hastings ' identical twin sister as well as the elusive `` A.D. '' . Alex believed the Liars knew who was accountable for Charlotte Drake 's homicide and also she impersonates Spencer due to being jealous of the upbringing that she was able to have . She was adopted by a wealthy British family that later abandoned her , forcing Alex to bounce around foster homes and orphanages for a large portion of her childhood . She is considered to be the deadliest antagonist of the series . 

Answer: answer: Alex Drake is a fictional character created by I. Marlene King and portrayed by Troian Bellisario on the American television series Pretty Little Liars.  She was adopted by a wealthy British family that later abandoned her, forcing Alex to bounce around foster homes and orphanages for a large portion of her childhood.  She is considered to be the deadliest antagonist of the series.