Alex Drake

Uber A is the main antagonist of Season 6b of the television series "Pretty Little Liars".

Uber A is an anonymous big bad who wishes to uncover the truth behind the murder of Charlotte DiLaurentis and he/she believes the Liars know the truth.

History
Uber A begins texting the Liars after Charlotte's death, using emojis instead of "A". Uber A threatens them to hand over Charlotte's murderer.

Unlike Mona and Charlotte, Uber A does not wear a black hoodie but instead wears various masks and disguises.

Eventually, after Uber A gives them a deadline, Hanna and Caleb hatch a plan to "deliver" the killer to Uber A, whom Caleb nicknames Amoji, by having Hanna lie and say it's her. The plan works and Uber A is supposed to meet Hanna in the Lost Woods Resort, where Caleb, Ezra and Aria are waiting outside to trap him/her. However, Uber A has other plans. Mary Drake sets off the alarm, while Uber A grabs Hanna through a whole in the floor and takes her to the Church. Uber A then takes the others and thanks them for giving shim Hanna, signing the text as "A.D."