Answer
Sasha Pieterse's co-stars in Pretty Little Liars were Ashley Benson and Shay Mitchell. They were all part of the main cast of the show, which ran from 2010 to 2017. Pieterse played Alison DiLaurentis, Benson played Hanna Marin, and Mitchell played Emily Fields. The show was about a group of teenage girls who were stalked by an anonymous person who called themselves "A".