Played by: Janel Parrish
TV Show: Pretty Little Liars
On Pretty Little Liars, Jane Parrish plays Mona Vanderwall, a Rosewood student who systematically transformed herself from a nerd into the current queen bee. After being revealed as the infamous “A” at the end of season 2, Mona vowed to ruin the lives of the Liars. Mona claims that she became "A" to get revenge on the Liars, whom she thinks stole her BFF Hanna from her. Sadly for Mona, that revenge has to be plotted from the Radley Sanitarium, a mental institution where she currently resides.