Mary Drake

Mary Drake is one of the main antagonists of season 6 on the television series "Pretty Little Liars", though she is hidden until the end. She is portrayed by Andrea Parker.

She is the twin sister of Jessica DiLaurentis and the mother of CeCe Drake/Charlotte DiLaurentis.

History
Spencer, Toby and Mona find a file which reveals that Charlotte was actually the child of a patient named Mary Drake and adopted by Jessica and Kenneth.

Later, Darren Wilden, who had been haunting Ali all throughout the episode, pulls off his face, revealing that he is wearing mask and underneath is Elliott Rollins. A woman who looks identical to Jessica approaches him and tells him he did well. He then greets the woman as Mary, revealing that Mary Drake was the twin-sister of Jessica DiLaurentis.