The A-Team

The "A-Team" is a secret group of people who use the psuedonym "A" to threaten the liars Aria Montgomery, Hanna Marin, Spencer Hastings, Emily Fields, and Alison DiLaurentis when she was still alive. Mona is the only known member of the "A-Team" so far, as revealed in "UnmAsked."

When Mona Vanderwaal was revealed to be "A," she tried to convince Spencer Hastings to join, what she referred to as the "A-Team." She also alludes to it when she says "You had to earn it, the right to be a part of it." After, Spencer asks her what she's going to do now, because doesn't A always have a plan? Mona replies with "Yes, she does." After Mona was admitted into the Radley Sanitarium, we hear in her mind that everything is going exactly as they planned. A mysterious person in a red jacket visited her and Mona told her that she did everything she told her to do.

Season 1
In "Keep Your Friends Close," the summer season finale of season one, the climax is reached when Hanna seems to figure out who "A" is, while spying in the forest. But before she can reveal the identity of "A," she is run down by a car while running to the other liars, and loses consciousness. Just then, the girls receive a text from "A" claiming responsibility for the hit-and-run.

Later in the hospital, in "Moments Later," Hanna tells the girls that Noel Kahn wrote the message on the back of Ezra's car, and he is presumed to be "A." (However, this is proved untrue when "A" plants the answers to three midterms in Noel Kahn's locker, because he was going to tell the principal that Aria and Ezra were dating.) "A" also leaves a message for Hanna on her cast, meaning that they had paid Hanna a secret visit in her hospital room.

In "For Whom the Bell Tolls," "A" saves Spencer from being murdered by Ian. "A" kills Ian in the process by hanging him. "A" takes Ian's body with him/her.

Season 2
In "UnmAsked," Mona attends the Rosewood Masquerade Ball with the other girls and later goes with Spencer to the Lost Woods hotel, after Spencer deduces that "A" had rented the room next to the one Alison was staying in. In the room, they find sketches of a Black Swan costume and conclude that "A" must be wearing it at the ball. Mona offers Spencer a stick of gum, but Spencer turns her down. While going through A's belongings, Spencer locates a gum wrapper from the same brand of gum Mona just offered her. She tells Mona that she changed her mind and that she'd like a stick of gum after all. Mona agrees, but says she doesn't have any more on her, but that she can go get some out of her car while she goes to call Hanna. She leaves the hotel room while Spencer continues to search. A few minutes later, Mona returns to the room and angrily says "I found the gum!" Spencer looks up from the book and says "You didn't call Hanna...because you're "A." Spencer turns around and we see Mona wearing a black hoodie. Mona admits she's "A" and congratulates Spencer on figuring it out, right before knocking her out.

Spencer wakes up in a car with Mona driving recklessly towards Lookout Point. Mona says that she wants Spencer to join the A-team. Spencer asks if the reason Mona became "A" was her anger at them for letting Alison bully her. Mona laughs and says that she got over that a long time ago. Mona reveals that she became "A" because she hated them for stealing Hanna's friendship from her. Spencer pleads with Mona to stop, encouraging her that Hanna is still her friend. As they drive, Spencer is secretly recording their conversation on her phone and sending the video to Aria's phone. Aria, Hanna, and Emily leave the ball immediately and drive to Lookout Point. When they show up, Spencer and Mona struggle, resulting in Mona falling off the edge. Spencer reaches out, trying to save her, but fails.

Mona was later put in Radley Sanitarium where she is visited by a mysterious stranger in a red jacket who seems to be the one giving "A" orders.

Season 3
In Season 3, it is confirmed that Mona isn't the only "A." While Mona is still in Radley Sanitarium, the Liars are still getting texts from "A". Also it is revealed that after the events of "UnmAsked," Spencer, Aria and Hanna returned to "A's" lair and all of "A's" possessions had been removed. Spencer also mentions several occasions where Mona was with them at the same time they received texts from "A," proving that Mona wasn't the one who sent those messages. This implies that at least one other "A" exists.

At the end of "Blood Is The New Black," the new "A" is seen buying various black sweaters and gloves while wearing a red hoodie. The cashier says, "You buying this for 'a team?'"

In The Remains Of The "A", Holden is seen with Emily from "That night". Also, Ezra is seen with alot of money in his drawer, which may suggest he was the one Jason Dilaurentis wrote a check to. This could possibly mean that either or both of them are members of the "A" team.

In Single Fright Female the A-Team seems to be taking action.

A's Lair
A's lair is "A|A's" base of operations. It is where "A" would go to think of plans, send texts, create messages, and find ways to torture the girls. Its is located in Room 2 of the Lost Woods Resort. The room contains pictures, newspaper clippings, and dolls resembling the girls and Alison. There is a hole in the wall behind a picture frame so "A" could watch Alison in Room 1 next door. Spencer concludes that A was stalking Alison. This is where Spencer figures out Mona is "A," due to the gum wrapper and cashmere sweaters.

Trivia

 * In "UnmAsked," Jenna, Lucas and the Black Swan are seen together. Considering the events of the Season 2 season finale, the Black Swan may be a member, which suggests that Melissa, Jenna and Lucas are also part of the "A-Team."
 * Considering that The A Team is harming Hanna the most, then the A Team members may be someone close to Hanna, like Wren or Caleb.
 * It's further speculated that Jenna Marshall is on the A-team because during "UnmAsked," she meets an unseen person in the park and hands them an unknown item with the instructions "you know what to do." Some believe this person to be the same person who visits Mona at the end. This might make sense if Mona and Jenna formed a friendship after Halloween 2008, as alluded to in "The First Secret." This would might also mean Noel is on the A-Team, since he had been helping Jenna and the whole relationship and breakup with Mona was staged.
 * The leader of the team could be the mystery person seen at the end of unmAsked wearing a red coat, just as it could be the same person seen at the end of blood is the new black, while wearing a red hoodie buying Black hoodies and gloves for a "team"
 * In "Blind Dates," "A" sends Emily a box of Danby merchandise and handwritten note which reads "SO HAPPY TO HAVE YOU ON OUR A -TEAM!"
 * Producers revealed Mona didn't do two of the things "A" did. This is most likely Emily's massage (She was with Hanna) and killing Ian (She has no known connection to him).
 * The next of the "A-Team" members was revealed in "The Remains Of The "A" to be either Holden Strauss and/or Ezra Fitz. It was also, possibly, Paige and Maya (before she died).
 * It's possible the leader is a woman. In "UnmAsked", when Spencer asked if "A" always has a plan. Mona answers "Yes, she does."
 * It's possible that the leader wears red while the recruiters wear black. Such as the person who visited Mona in a red coat could of been the same person who wore a red hoodie and bought a pair of black gloves and black hoodies possibly for their recruiters.
 * Jason DiLaurentis thought that Ian started the N.A.T. Club to take photos and videos for someone and not for himself. (The Remains of the A)
 * It is revealed in "What Lies Beneath" that Noel is a very likely A Team member. Emily and Hanna got locked in The Kahn's Cabin, and Noel sent Spencer the security footage from the night (same date and time) that Maya was killed.
 * The team seems to take action in "Single Fright Female".
 * The next "A-Team" member will be exposed in "The Lady Killer"

Possible "A-Team" Members

 * Holden Strauss - He knew Maya, and went to parties of Noel's, who have never seem to have had contact
 * Ezra - He lied to Aria about his family and Maggie. It was also thought that he got 50k from Jason, which was the reward for info on Ali's case.
 * Ian - May have started the N.A.T. Club to film people for someone other than himself, Jason, and Garrett.
 * Jenna - She meets an unseen person in the park and hands them an unknown item with the instructions "you know what to do." She was also seen associating with the Black Swan.
 * Lucas - He had molyzapam in his camera bag, which was in the flask Emily and Paige drank out of.
 * Noel - He faked going out with Mona to help Jenna.
 * Garrett - He gave something to Jenna to hold onto. It was a page from Ali's autopsy report.
 * Courtney/Alison - Jason says he has more than one sister. Courtney was crazy, and sent Ali off to Radley, and befriended the liars. (If this character exists in the TV show)
 * Melissa - She hated Ali for dating Ian at the same time as her, so she threatened her. She is also the Black Swan.
 * Paige - She has a violent past with Alison.
 * Wren - Has full access to Mona.
 * Nate - He arrives in town right after Maya's murder. This is suspicious, as Maya never mentioned Nate, or that he applied for Hollis like Nate said he had.