Red Coat

"I did everything you've asked me to do!"

- Mona to Big A

Big A is an unknown character, responsible for the creation of "A" and the A-Team. Little information is known about this person, who only makes appearences wearing a red trench coat. Big A is considered to be the main A and the leader of the A- Team, as he/she is the one calling the shots, and telling his/her workers (aka minor A's) what to do (such as ordering Mona to hit Hanna with a car, ordering Toby to steal Alison's body and ordering the deaths of Ian Thomas and Garrett Reynolds). Though this characeter is considred to be the main A, he/she has little to no physical  involvment with the Liars since he/she orders his/her team members to actually do the things that A has been known to do to the liars.

We have only seen Big A twice. The first time is at the end of the season two finale, unmAsked, where he/she visits Mona after being revealed as an A- team member. Big A is seen wearing a red trench coat. Mona looks up to Big  A, and says: "I did everything you've asked me to." From this point, it becomes clear that he/she is the leader of the A- Team. The second time is at the end of the season 3 episode of "Blood Is The New Black", where he/she is seen buying black hoodies and gloves for his/her workers. Again, he/she is seen wearing a red hoodie. The store owner says to Big A: "So, are you buying this for a team?".

It is possible that Mona was talking to Big A in "The Lady Killer", as it was clearly shown that Mona was taking orders from someone when she said: "I understand" on the phone.

It is possible that Big A makes his/her workers physically do the things that A does to the liars because he/she does not want their identity to be traced back incase the Liars discover a new -A team member, or so called "minor A". This is similar to how in the mafia, the boss/don tells his capo's what to do, who in turn give orders to their soldiers. While the A- team members are known to wear a black hoodie, black gloves and black pants, Big A makes their appearence in a red trench coat or a red hoodie.

The Beginning
A has gone into buisness since Halloween 2008, when he/she began tormenting Alison DiLaurentis, at the time unbenowest to the liars. When the episode premiered, it was mostly unknown to the audience that A was in fact a team of people. Most likely, Big A was responsible for the creation of A and the A-Team, and that members such as Mona Vanderwaal and Toby Cavanaugh were recruited later on.

Season 2
In the season 2 finale of UnmAsked, it has been revealed that Mona is in fact A. After Mona knocks Spencer Hastings unconsious and puts her in her car, Mona gives Spencer an "offer she can't refuse": either join the A-Team, or die! After the fiasco on Lookout Point, and when Mona is taken to the police station before departing for Radely, she says in a monologe: "They think it's over! Loser Mona's going to the nuthouse and those precious liars think they can sleep with their windows open and their doors unlocked . Don't they know that's what we want!" It now becomes confirmed at this point that A is a team of people.

At the end of unmAsked, we see Mona sitting in her bed at theRadley Sanitarium. A visiter wearing a red trench coat, much similar to that of Vivian Darkbloom, stands before Mona, to whom she says: "I did everything you've asked me to!" It is highly implied that this is the Big A, and that he/she is the main A and the leader of the A team (who calls the shots and controls their workers/minor A's). It becomes quite clear that though Mona is part of the A-Team, and has physically done everything that A has done to the Liars, she is simply working for the Big A, who tells her what to do (hitting Hanna with a car, and other things).

Season 3
By season 3, it is officially confirmed that A is a team of people: the A-Team, and that due to the ending scene of the season 2 finale, this team is controlled by the main A: Big A, who calls the shots.

In the second episode of season 3, Blood Is The New Black, we see Big A once more. Wearing a red hoodie, he/she is seen buying black hoodies and gloves for his/her workers. The store owner says to Big A: "So, are you buying this for a team?".

Throughout season 3, there is a "New A" tormenting the Liars. In The Lady Killer, it is revealed that Toby Cavanaugh is this A, and is also part of the A-Team! The dramatic irony is that the Liars don't seem to understand that both Mona, and the New A, are simply workers for the Big A. In the same episode, we also see Mona possibly talking to the Big A on the phone since Mona learns from the other person that there is a "change of plans". Since Big A is usually the one planning out all of the A schemes, it seems as if it really was him/her.

It is obvious at this point that there are much more A-Team members then just Toby and Mona.

Identity
There is almost no information about Big A or what their motives are. Also, fans have almost no clues considering the fact that Big A never physically confronted the Liars. However, many fans have made certain theories:

It has been widely speculated that Big A is Alison DiLaurentis, or a twin of some sort (see Courtney DiLaurentis, a book character). Some fans suspect her becuase Big A makes their appearence wearing a red trench coat, similar to the red trench coat of Vivian Darkbloom (the alter ego of Alison DiLaurentis, who used this personna to supossedly find out who A is). Supporters of this theory think that Ali (or Courrtney) had a twin who hated her, and started the A-Team to ruin the lives of her and the Liars.

Another theory that recently started trending is that Aria Montgomery is in fact the one behind all of this. Fans have pointed out to the fact that Aria recieves almost little to no torment from A, never had any confontation with A (until the season 3 Halloween episode), along with a wide range of clues taken from the show. They also point out that Aria was the last one seen wearing Vivian Darkbloom's coat, before we see Big A wearing the same coat when visitng Mona in UnmAsked. They also point out that Aria showed no hesitation, or awkwardness, when she was about to wear her dead best friend's coat for the "first time". Another importnat clue is that in The Goodbye Look (season 2 episode 2), Mona says to Aria: "Hey, Big A!"