<P> Emily Fields (Shay Mitchell) (season 1--7) is the "jock" of the group . A highly competitive swimmer, she is considered the star of Rosewood's swim team . She is shown as a sweet and shy character . For a short time Emily lives with Hanna, after her mother moves to Texas to live with Emily's father, who is stationed in Fort Hood . She begins to question her sexuality because of her feeling for Alison, but later accepts the fact that she is a lesbian and starts to date girls, including Maya, Samara and Paige . She eventually enters a relationship with Sara Harvey, until she discovers that Sara is Red Coat and the ally of Big "A". </P> <P> Alison DiLaurentis (Sasha Pieterse) (season 1--7), was the former "Queen Bee" of her clique and the most popular girl in school before her disappearance and alleged death . Although she cared for her friends, she enjoyed using their deepest secrets against them to keep them in line . Charming and manipulative, Alison was skilled at finding ways to blackmail everyone, and many people hated her . She knew everybody's secrets, but since she's been gone her friends are beginning to realize how little they really knew about her . She is revealed to be alive and on the run from "A ." When Shana is killed, who they think was "A," Ali returns to Rosewood . In the Season 5 summer finale, Mona reveals that Mrs. DiLaurentis had an affair with Bethany Young's dad and Alison found out and lured Bethany to Rosewood . Mona tells Aria that she now has proof that Alison is "A". Before Mona can show the Liars the proof, "A", blonde hair flowing from her hood, breaks in a kills Mona . Alison is later seen at the Mona Vanderwaal's crime scene . She smirks and walks away, implying that Alison may be "A". After the Liars abandon her, she forms her own army consisting of Jenna, Sydney, Holbrook, Cindy and Mindy, and seemingly Cyrus . In the winter premiere for the fifth season, Alison is arrested for Mona's Murder after evidence is provided against her, but it is later revealed that Mona was working with "A" to frame Alison because that's what "A" wanted and Mona wanted to find out "A's" identity . This proves that Alison likely wasn't "A". Upon the police discovering that Mona is alive, Alison is cleared of her charges and has now returned home . </P> <P> 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 CeCe 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 CeCe reveals that it was her who hit Alison . </P> <P> Alex Drake (Troian Bellisario) (season 7) is the twin sister to Spencer Hastings and the half - sister of Charlotte Drake, Melissa Hastings, and Jason DiLaurentis, as well as the daughter of Mary Drake and Peter Hastings . Alex was given up for adoption to a British family by Mary during her birth . Alex grew up in orphanages, not knowing anything of her real family, until the day that Wren Kingston came into her bar and immediately thought she was Spencer . She clarified her real identity and he revealed Spencer and everything to her . Wren introduced Alex to Charlotte and the two of them formed an immediate bond together, spending every moment with each other until Charlotte left to go back to the U.S. to play the game some more . Alex eventually learned of Charlotte's death and decided to avenge her by becoming Uber A. At first, Alex sent the Liars threats, using only Emojis to sign the texts . However, after kidnapping Hanna, Alex begins using the alias "A.D." to sign off her texts . Alex convincingly masquerades as Spencer multiple times to be with Toby and trick the Liars . After the game ends, Alex goes back to London but returns a year later to kidnap Spencer and take her place, along with Mary and Mona's help . Alex explains herself to Spencer and reveals her entire story, also revealing that she has killed Wren to avoid having to break up with him . She also kidnaps Ezra . Spencer and Ezra escape and Alex is detained . However, Mona manages to kidnap both Alex and Mary and locks them away in her own personal dollhouse in France . </P>

Who plays the character a in pretty little liars