The Liars

Spencer Hastings, the "smart girl" of the group. She is an extreme perfectionist who always tries to please her wealthy parents who are clearly more affectionate and caring towards her older sister Melissa Hastings. Spencer was the only person who was brave enough to stand up to Alison, and may have been one of the last people to see her alive.

Aria Montgomery, the "artsy girl" of the group who moves back to Rosewood with her family after spending a year in Iceland. At a bar, she meets Ezra Fitz and kisses him, only to discover on her first day of school that he is her English teacher. They decide to continue their relationship in secret and do so for some time, until eventually making their romance public.

Hanna Marin, the "it girl" of the group who struggles with self-image issues and an obsessive desire to lose weight. A "loser" while Alison was alive, Hanna subsequently transformed herself into the most popular girl in school along with her best friend, Mona Vanderwaal.

Emily Fields, the "jock girl" of the group. Emily was closest to Alison before her disappearance and was also in love with her. A closeted lesbian, Emily was later outed by "A".

Alison DiLaurentis, former "Queen Bee" of her clique and the most popular girl in the school before her disappearance and 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 was hated by many people. She was killed a year prior to the beginning of the series. The show's main premise revolves around the mystery of Alison's murder.

Mona Vanderwaal, She becomes the new fifth liar in season 4. While In Alison's time, Mona was desperate to be in the girls' group. She was often teased and ignored by Alison, and she was a total dork. After Alison dissapears, Mona befriends Hanna and transforms themselves into the popular crew of Rosewood. Mona was the first A revealed. Her motives were that the liars took Hanna away from her. She is sent to Radely, but is released several months later. Due to a number of factors, Mona becomes the new target of A/Red Coher as a new addition to the group.