Mona Vanderwaal

"It's easier to forgive an enemy than it is to forgive a friend."

- Mona Vanderwaal

Mona Vanderwaal is a character on Pretty Little Liars. She was the main antagonist of seasons 1 and 2, the secondary antagonist of season 3, an anti-hero in season 4, the initial main antagonist turned heroine in season 5, and an anti-heroine in seasons 6 and 7. She is also the main antagonist of the first four books of Pretty Little Liars book series.

Mona is revealed to be the first and original "A" in both the television and book series. In the TV series, it is also revealed that she bludgeoned Bethany Young to unconsciousness (thinking she was Alison DiLaurentis) and deceived Melissa Hastings into burying her alive, killing her. In the book series, she falls to her death after her reveal, however in the television series, she survives and continues being "A" before eventually becoming an anti-hero.

Book series
Mona was a very intelligent girl who desired to be friends with the main characters and Alison. They shunned her, leading Mona to seek to revenge on the girls. Mona found Alison's diary which contained many of their secrets. She even befriended Hanna to put her scheme into action. Along with Hanna she became one of the most popular girls in school. Mona then adopted the identity of A which she used to blackmail the girls. They thought it was Alison at first but after her body was found they were baffled. Mona then started becoming more vicious in her actions such as outing Emily to her parents and blaming Spencer for Alison's death.

Mona eventually made a mistake when she texted Hanna using her own phone instead of the one she bought for her plans. This caused Hanna to realize she was A. To prevent her from telling the other girls, Mona ran Hanna over with her car. Hanna had temporary memory loss but Mona knew there was a chance Hanna could regain her memories. Mona then sent herself text messages from A to throw suspicion off of her. Mona later tricked Spencer into getting into a car with her by telling her they were going to the police station. Hanna regained her memory and texted Spencer warning her of the danger. Spencer tried to escape but Mona realized this and prevented her from doing so. They headed into a deserted area of Rosewood where Mona told Spencer she was A explaining she did it because she had been shunned by the girls so she wanted revenge on them. Another part of it was because she had seen them accidentally blind Jenna with a firework.

Mona told her she knew their secrets from Alison's diary and asked Spencer to be A with her. Spencer refused causing Mona to start choking her. Spencer then killed Mona in self defense by pushing Mona off a cliff to her death.

Television series
Mona's role in the television series is very similar to the books until the end of Season 2. Instead of dying, she ended up being locked up in an insane asylum. Mona was visited by somebody in a red coat telling them she had did everything that they wanted. Hanna started visiting Mona in the asylum but her Mona showed no signs of recognition at first before Hanna gave her a make-over. The next time Hanna visited her, Mona asked about the new A and later Caleb visited Mona warning her to not mess with Hanna. Later, Mona managed to sneak out of the asylum dressed as a nurse where met up with another member of the A team revealed to be Toby.

Mona told him she was disappointed that their plans had not worked out. During Halloween, Mona snuck out of the asylum again and wore the same costume as Caleb. This fooled Hanna until she saw the mask on that Mona made to her her identity. She apparently made her way back to the asylum pretending to be asleep when a nurse checked on her.

Trivia

 * Mona is arguably the "bigger bad" to Alison in the books since she is the one who began the game in the first place.
 * Mona was an outsider who was bullied by Alison and wanted to be friends with her.
 * She started the "A" game just to harass Alison for her bullying and began it again to prevent the Liars and Hanna from becoming friends again.
 * She became somewhat reformed in season 4 after being kicked off the "A"-Team. In season 5, she started out as the main antagonist before becoming an anti-hero again, which she remains today.
 * She also become a reformed mean girl in seasons 5 and 6.
 * She was similar to Rachel Gatina from One Tree Hill, an outsider and a geek. She had a million dollar makeover that transformed her into a mean girl.
 * Mona was revealed to be the person who hit Bethany Young with a shovel, mistaking her for Alison from behind because they were wearing the same outfit and had the same hair color (blonde). She claimed to have hit her because she was upset over everything she did to her, saying she "could hear every awful thing she said all at once" when she hit her. Bethany was then later buried by Melissa Hastings.
 * Mona supposedly died in the twelfth episode of the fifth season, titled "Taking This One to the Grave". She was attacked by Big "A" before the Liars found blood all over the walls in her house. Her "corpse" was shown at the end of the episode, but it was revealed that "A" had drugged her with something that caused her to not move and look like as if she was dead. The blood found in the house was a result of her drawing blood from herself since she was originally planning to fake her own death. "A" was holding her captive for several months, though she eventually escaped.
 * Mona is a unique character in that for the TV show she starts off as the Big Bad for the first two seasons, becomes a henchmen in the third season, while also being somewhat of a Bigger Bad since the "A" idea was hers, then becomes an anti-hero in season 4, initially a Big Bad again in season 5 before becoming an anti-hero once more and is currently an anti-hero.