Alison's Attempted Killer

Alison's Attempted Killer is the anonymous character in Pretty Little Liars who attempted to kill Alison DiLaurentis by hitting her on the head with a rock during the Liars' sleepover on September 7, 2009. In Season 5, we learn this person is indeed the current "A".

We learn in "A is for Answers" that the person who tried to kill Alison and the person who buried her are two different people. Jessica DiLaurentis saw who hit Alison with a rock, and subsequently buried her daughter alive believing she was dead and in an attempt to protect the attacker.

Suspects
The Liars at first suspected Toby Cavanaugh to be Alison's killer, due to the fact that he was blamed for "The Jenna Thing", giving him a motive. He was also suspected by the Rosewood Police Department after they found Toby's sweater with Alison's blood on it. He was cleared of his status later on when other evidence came forward.

The next suspect was Ian Thomas, who the Liars suspected had had an affair with Alison. His name was found carved on a tree along with Alison's and 'A' sent the Liars a video of Ian and Alison at The Kissing Rock the night she disappeared. The Liars told the police about their suspicions but were ignored due to Ian's good reputation. Emily later found the N.A.T. Club videos which Alison had stolen, suggesting Ian had killed her because she knew about them. Ian was later killed and a suicide note telling the police of his guilt was left by his body, although this was later proven to have been faked by 'A'. The Liars also saw footage of Ian leaving Alison at the Kissing Rock, clearing him of suspicion.

Alison's brother, Jason, was suspected by the Liars in Season 2 as he woke up the morning after Alison's disappearance with a note in his pocket saying "I know what you did". He was also suspected at the beginning of Season 5, as Mrs. DiLaurentis must have known Alison's attacker if she protected them, leading the Liars to think Jason hit Alison with the rock.

Garrett Reynolds was suspected of Alison's murder due to the fact that he stole page five of Alison's autopsy report. He was subsequently arrested and charged with both Alison and Maya's murders. His innocence was proven when his blood was not found on the anklet and Lyndon James was revealed as Maya's stalker and murderer. Jenna, however, thought he killed Alison as he pretended to with Spencer's old field hockey stick.

Detective Darren Wilden was the main suspect in the second part of Season 3 as it was revealed that he may have had a sexual relationship with Alison the summer she disappeared in Cape May, making him to possibly be Beach Hottie. CeCe Drake supported this theory as she believed Wilden got Alison pregnant and killed her to cover it up.