<Li> Sasha Pieterse portrays Alison DiLaurentis, one of the five Liars and the former "Queen Bee" of her clique, and the most popular girl in school before her disappearance . She enjoys using people's deepest secrets against them to keep them in line . Charming and manipulative, Alison managed to manipulate all four of her friends in one way or another and is skilled at finding ways to blackmail others . It was later revealed that Alison is alive and was on the run from "A". After the five - year time jump, Alison marries a man posing as Dr. Elliott Rollins, who was her sister Charlotte's psychiatrist . In the beginning of Season 7, Alison finds out that he is not the "good" man that she thought she married and with the help of the other girls, they manage to kill him before he kills them . Alison is now an English teacher at Rosewood High . It is also revealed in season 7 that she is pregnant with Emily's baby . Shortly after, she admits to being in love with Emily and enters a relationship with her and intends to raise the baby with her.In the series finale, she is raising twin girls, Lily and Grace, later on in the episode she proposes to Emily . </Li> <Li> Tyler Blackburn portrays Caleb Rivers, the high school boyfriend and later husband of Hanna Marin, and a professional hacker . It is revealed in season 1 that he was in the foster care system and slept in school or public places the majority of the time to avoid staying with his foster family . For a brief time he moves into Hanna's basement before moving in with Lucas . He also reconnects with his biological parents . He departs the show mid-season 4 to go to Ravenswood, which was a sister spin - off show of Pretty Little Liars . He returns in the 100th episode with a haunting secret which causes tension between him and Hanna . They both begin drinking, him to forget Ravenswood, her coping with Alison's return to Rosewood . After the time jump, it is revealed that he and Hanna broke up due to them working too much and he begins dating Spencer causing a love triangle between the three of them . In the mid-season 7 finale, he confesses his feeling for Hanna leading to them having sex prompting them to get back together . In "Choose or Loose", they elope in the courthouse and in the finale, Hanna announces she's pregnant . </Li> <Li> Janel Parrish portrays Mona Vanderwaal, the original and first "A". She is the person who stalked Alison before her disappearance, and did this as revenge for Alison crowning her "Rosewood's biggest loser". After Alison disappeared she became best friends with Hanna Marin and they transformed themselves into the most popular girls at school, taking Alison's place . In the season two finale she is exposed as "A" and sent to Radley Sanitarium, where she is visited by CeCe Drake (Charlotte), who takes Mona's place in the "A" game . In Season 3, she continues working as "A" and by the end of the season is kicked off the "A" team and becomes a victim of "A" along with the other girls . In Season 4 she helps the girls out with their investigations of the new "A". In season 5 she creates an army so as not to be intimidated by Alison's return . Later in the season, she fakes her own death to ferret out "A" but is kidnapped by "A" and imprisoned in "A" 's dollhouse . After the time jump, Mona is working for Veronica Hastings' rival for State Senator, and is revealed to be Charlotte Drake's killer . </Li> <Li> Andrea Parker portrays Jessica DiLaurentis / Mary Drake, twin sisters . Jessica is the mother to Alison and Jason, while Mary is revealed to be the mother of Charlotte and Spencer . Mary was admitted to Radley Sanitarium for most of her life, but has now returned to Rosewood . During the fourth season, Mary kills Jessica and attempts to frame Peter Hastings for it . However, this is not revealed until season 7 . She comes back to Rosewood later, now allied with Archer Dunhill . In the nineteenth episode of season 7, she takes the blame for the death of Archer Dunhill so the Liars won't have to go to prison . In the season finale, it revealed that she escaped prison with the help of Mona so that she could ally with Alex Drake, her other biological daughter, Spencer's twin sister who is revealed as "A.D.". </Li>

Who is an a in pretty little liars