It was recurring mystery during the finale seasons of Pretty Little Liars, so who really killed Big "A" Charlotte? Pretty Little Liars is based on a popular book series by author Sara Shepard and follows a group of girls threatened by a mysterious stalker known as "A." This mystery villain threatens to expose their deepest, darkest secrets to the town, which only becomes darker when their missing friend Alison turns up dead. Of course, Pretty Little Liars is a show that wallowed in shocking twists and character turns, so things were rarely as they first appeared.
Pretty Little Liars was never a critical darling but it earned a loyal following, who stuck with it throughout seven twisty seasons. The show's mix of Heathers-style black comedy and murder made it a supreme guilty pleasure for many. The series also spawned two spinoffs; supernatural series Ravenwood and Pretty Little Liars: The Perfectionists, which follows the continuing adventures of Alison DiLaurentis and Mona in a new town; both spinoffs only lasted for a season.
Pretty Little Liars eventually revealed it was Mona who was the original "A," though many others would take up that mantle throughout the show. Another major villain was Charlottle DiLaurentis, played by Vanessa Ray (Blue Bloods). Charlotte caused many, many headaches for the Liars as Big "A," but after being discovered and spending years in a psychiatric hospital, she's released. She later dies in an apparent suicide in season 6 episode "Of Late I Think Of Rosewood," but it becomes clear she was murdered.
In Pretty Little Liars season 7 episode "Farewell, My Lovely" it's revealed Mona killed Charlotte. Mona confronted Charlotte in a church steeple, well aware Charlottle hadn't really changed despite her therapy and intended to torment the Liars again. Charlotte confirms this and taunts Mona, who pushes her to the edge of an open window and threatens to kill her. Mona eventually decides not to push her over but warns Charlotte to leave her friends alone. This leads to a vicious fight where Charlotte is accidentally killed by a stray piece of metal when Mona throws her against the wall. This was an accident on Mona's part but she hides it anyway.
It wasn't a huge shock to learn Mona was behind Charlotte's death on Pretty Little Liars, though the motives behind it were still a surprise. It sounds like Charlotte was gearing up for some old-school psychological torture on the gang and hadn't changed one bit during her time in the hospital.