Alison Lauren DiLaurentis is a fictional character in the Pretty Little Liars book series, its television adaptation, and the spin-off series Pretty Little Liars: The Perfectionists. The character was created by American author Sara Shepard.

Melissa Hastings is a fictional character in the Pretty Little Liars franchise. Created in 2006 by Sara Shepard for the book series, the character was later reworked by I. Marlene King, the developer of the television series, in which she is portrayed by Torrey DeVitto. An antiheroine, Melissa is sister to protagonist Spencer Hastings, and the daughter of Peter and Veronica Hastings. She is a fierce woman who does everything to succeed in her life goals. In print, she is a guest character, while on screen Melissa has a much bigger presence in the story.