Mona Vanderwaal

Mona Vanderwaal is a fictional character in the Pretty Little Liars book series, its television adaptation, and the spin-off TV series Pretty Little Liars: The Perfectionists. In the TV shows, she is portrayed by Janel Parrish. Introduced in Pretty Little Liars as Hanna Marin's best friend, Mona initially harbors a grudge against the protagonists, using her intelligence and resources to torment them anonymously as "A". In the third season of the TV series, Mona gains a partner who eventually takes control from her. Afterward, she forms an unstable alliance with the protagonists, becoming a victim of her own creation. Considered the most knowledgeable character in the series, Mona is versed in computer hacking, foreign languages, singing, empathy, and manipulation. Though introduced as a villainess, she eventually takes steps toward redemption. Mona is the first 'A' in the show and the book. Initially a supporting player, the TV character gained much popularity among viewers and critics, drawing recognition from Entertainment Weekly, CNN, MTV, and others, prompting producers to expand her role. In March 2015, PrettyLittleLiars.com named Mona the greatest Pretty Little Liars character. MTV also named her one of the best characters on television in 2014. During the TV series' run, producer I. Marlene King acknowledged Mona as a "beloved character." By the end of the show's run, Dana Getz of Bustle.com declared that Mona had become "the most important character in the series."