Before the death of his father, Luke Matheson was part of the in-crowd. However, he did a complete 180 and now is kind of a loner. He also seems to be in a romantic relationship with Remy and is very protective of his twin sister: Olivia.

Luke is at the Celebration talking to a girl in low voices, but she quickly leaves him. Outside the tent, Aria Mongtomery assists the girl out of an empty grave, and Aria asks if she was pushed by the guy she was with earlier, but she says that is her cousin and that he wasn't behind this. Luke arrives, tells her that the graveyard isn't safe and they leave.

Luke as a lone wolf with an old soul, whose trust is hard won but loyal untill the end.

Luke is Olivia's twin brother and first appears in the 2013 Pretty Little Liars Halloween special.

He has dirty blonde hair with blue eyes.