Alex Drake

Alex Drake is the main antagonist of Seasons 6B and 7 of the television series "Pretty Little Liars". She is the twin sister of Spencer Hastings and A|Uber A.

Unlike Mona and Charlotte, Uber A does not use the letter "A" but instead uses the alias "A.D." and emojis, prompting Caleb to call them Amoji.

History
Uber A is a close friend of Charlotte DiLaurentis. One day, Charlotte was killed by an unknown assailant. After her death, Uber A decided to find the killer and avenge Charlotte's death. He/She knew the Liars and threatened them to find the killer's idenity.

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.

Eventually, after Uber A gives them a deadline, Hanna and Caleb hatch a plan to "deliver" the killer to Uber A, whom Caleb nicknames "A-moji", 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 had other plans. They had Mary Drake set off the alarm, while they grabbed Hanna through a hole in the floor and takes her to the Bell Tower. Uber A then texts the others and thanks them for giving him Hanna, signing the text as "A.D.".

The Liars found a doll in a church that told them that they had 24 hours to give him Charlotte's real killer or Hanna will die. They came to the decision that Alison murdered Charlotte and they left a red sweater (that they think Alison wore while murdering Charlotte) for Uber A to take as proof. Upon finding the evidence, Uber A picks the sweater up and puts it in a bag. After Alison is put in a mental institution, she is turned delusional and insane by one of Uber A's helpers—Archer Dunhill, her own husband. Archer posed as a doctor named "Elliott Rollins" and married her to take her money, but he was also Charlotte's lover. He became Alison's doctor and therapist, and abused his power to torture her for "killing" Charlotte.

When Uber A discovers that Alison wasn't Charlotte's killer, they inform Archer to drop her off in the woodlands near the institution. When driving her there, Alison thought Archer was going to kill her, so she slammed his head onto the driving wheel and made an escape. As Archer chased her, he was accidentally run down and killed by the Liars who were trying to save Alison (because they thought he was going to kill her as well). They bury his body to cover it up, and Uber A uses this to torture them. The Liars begin receiving phone calls from a man who sounds a lot like Archer, and to make sure he is dead, they dig up the spot they buried him in and find his rotting corpse, confirming their suspicions on whether he was really dead or not. Uber A films this from afar.

Two of the Liars' enemies, Jenna Marshall and Noel Kahn, become Uber A's helpers. They begin to suspect Noel is A.D., and they use everything in their power to prove that he is. Hanna decides to abduct Noel, so that she can force him to confess he is A.D. However, Noel is able to escape when Hanna leaves him alone for a moment. The Liars track him and Jenna down in an abandoned building. Jenna, who is blind, obtains a gun and walks around trying to find them to shoot them. Alison, Aria and Spencer try to hide from her while being silent, and Emily and Hanna try to escape from Noel whom is trying to kill them both with an axe. While fighting, Emily knocks over Noel who falls onto the axe, being decapitated in the process. Off-screen, Sydney Driscoll, another accomplice of Uber A, shows up and shoots Spencer. She also rescues an unconscious Jenna who was knocked over by Mary Drake when she tried to finish off Spencer.

Sometime later, Uber A renews the game by sending the Liars a board game, called "Liar's Lament" At this point, A.D. is more focused on torturing on the Liars rather than finding Charlotte's killer. A.D. starts sending the Liars on several missions to uncover several secrets, such as Alison discovering that A.D. impregnated her with Emily's eggs. Everytime a Liar refuses to cooperate, A.D will send a clue to the police regarding Archer's death as a warning.

Helpers
Uber A is assisted in his/her game by helpers. Uber A's current known helpers are:
 * Jenna Marshall: Revealed in the seventh season, Jenna was revealed to have known about Charlotte and was friends with her at Welby. She is angry at her death. She was also being paid by Archer to assist them until his death.
 * Sydney Driscoll: Revealed in "Hold Your Piece", Sydney is Uber A's accomplice. She donates money to Vogel Vision Institute under the name A.D. for Uber A.
 * Aria Montgomery: Revealed in the seventh season, Aria joins the A-Team after Uber A gives her the offer, becoming their henchwoman and informant.
 * Mary Drake: Revealed in the seventh season finale, Mary works with Alex in her bunker.

Trivia

 * Uber in German means "superior" or "above".
 * Uber A will be the final "A".
 * The main suspects of the fandom are Melissa Hastings, Wren Kingston, and Lucas Gottesman. Wren was revealed to be a helper, Melissa's face was worn as a mask by Mona under orders from "A.D." and Lucas was a suspect.
 * Despite being referred to as Uber A, being called an "A" by characters, and being the final "A" ever, Uber A has never actually used the alias "A" during their game.