Jenna Marshall has had the most motive to torment the girls from the beginning. Why wouldn't she exact revenge for them blinding her? She came back to town for Ali's (Sasha Pieterse) "funeral" and she always seems to be involved in the plans to ruin the girls' lives. It turned out she wasn't the first or second A, but we know that she's definitely hanging out with A.D. now.
Photo Credits: Richard Cartwright/ABC; Bill Inoshita/CBS; Steve Granitz, WireImage; photo: Prashant Gupta / FX Networks; CBS Photo Archive, CBS via Getty Images; J. Vespa/Getty Images; ABC; NBC, NBC via Getty Images; Getty Images/NBC; Byron Cohen/Freeform; Monty Brinton, CBS; Showtime