Mona Vanderwaal (Janel Parrish) (season 1 – 7) is a former unpopular girl at Rosewood who longed to be accepted into Alison's group and was continuously mocked by Alison. After Alison's disappearance, Mona befriended Hanna and they underwent an "extreme makeover" together; as a result, they both became popular students. When "A" appears, Mona becomes jealous of Hanna rekindling her friendships with the other Liars. She dislikes Caleb and makes attempts to break Hanna and Caleb up, though to no avail. She becomes romantically involved with Noel, much to Hanna's disapproval, but is later dumped by him for Jenna. When "A" begins sending Mona threatening notes, she grows closer to the Liars. In the second-season finale, she is in fact revealed to actually be "A" when she and Spencer travel to the Lost Woods Resort to uncover "A"'s lair. She is committed to a mental institution, Radley, after being diagnosed with borderline personality disorder. Here, someone known as Big A takes the "A" game away from Mona and starts an "A-Team", consisting of Mona, Toby, Spencer, Melissa, Wilden, and Lucas. At Radley, Mona gives answers to Hanna concerning Maya's death. Possibly unbeknownst to Big "A", she secretly gives Maya's website to Hanna in code, leading them to eventually discover that Nate killed Maya. Mona reveals that a person in a red coat came along and changed the game, becoming the new "A". Mona later reveals she actually doesn't know who "Red Coat" is, and is basically expelled off the team for letting Spencer and Toby trick her. At the end of season three, Mona gets a text along with the rest of the girls in red font: You're mine now. Kisses! -A, implying she is now a victim of "A". Mona begins helping Ezra with his book in 4B due to him blackmailing her because of her illegal "A" activities. In the season 4 finale, Alison reveals that Mona helped her the night she was hit over the head and convinced her to go into hiding. In Season 5, she starts an army of Alison haters to prepare for Ali's return. The team consists of Lucas, Melissa, Jenna, Sydney, and various other people that were treated badly by Alison. In the season five mid season finale, she is killed by Big "A" after acquiring information that proves Alison is Big "A". In the second half of the season, it is revealed that Mona never thought Alison was Big "A" and instead, it was a plot by her and Big "A" to get Alison into jail. Mona was to fake her death as part of this plan, so that she could find out Big "A's" identity, and in the fifth-season finale, it was revealed that Mona is really alive and being forced to "be" Alison inside Big "A"'s Dollhouse. She escapes the Dollhouse with the other girls in season six, and ends up finding out Big "A's" true identity to be Charlotte Drake, alongside the others. During this revelation, Mona realizes that she was the one who hit Bethany Young with a shovel that night, believing she hit Alison, but discovering the truth once Charlotte reveals that it was her who hit Alison. After the five-year time jump, Mona demands to be at Charlotte's hearing over her release and breaks down. Later, she is shown to be working for Veronica Hastings' opponent. When A.D., the newest incarnation of A, sends the girls a game board that forces them to do things, Mona steels it to discover its secrets. She is the one to reveal the liars Aria's allegiance to the A.D, and reveals to Hanna that she killed Charlotte in an act of self-defense. In the series finale, Mona is again in a sanitarium thanks to the game's effects on her. Hanna takes her in when she is released, and Mona once again joins the A.D. team when Wren Kingston, comes to Welby Sanitarium to kill her. Mona confesses to the liars she joined the A.D. team, but also gives them A.D's location. Mona is there when they discover A.D's identity to be Spencer's twin sister, Alex. Mona and her French boyfriend take Alex and Mary Drake to a cell in France, revealing she is the ultimate "A," and has won the game. As a byproduct, Mona outlasts the liars as the final person seen in the show.
