Luke was portrayed by Andy Chambers. There is some confusion regarding his name as Luke is sometimes credited as "Luke Cassellis" on cast lists online, but is referred to as "Luke Matthews" on the show.
Luke Matthews is an occasional character in Degrassi Junior High and Degrassi High who becomes known for drug use and provision. He provided the drugs that caused Shane McKay's serious injury, leaving Shane brain-damaged. Yick Yu hangs out with him.
Season 3In He Ain't Heavy, Luke tries out for the basketball team.
In Taking Off (1) he offers Shane acid before they get into the concert. The next day when Shane goes missing, Luke lies to the police and tells the officer Shane wasn't doing drugs and that he doesn't know anyone who uses drugs.
In Taking Off (2) Caitlin asks Luke if he knew what happened to Shane, but he says he doesn't. Mr. Raditch then asks the class if they have any information regarding Shane, they should come forward to the police. The police then call Luke out of class to tell him that they found Shane under a bridge. They call him out on his bluff, revealing that many witnesses have come forward stating that Shane was on drugs. Luke confesses that Shane might have taken acid.
In Making Whoopee, Luke asks Tim how Shane is doing in the hospital. Tim says that he is still unconscious and Luke should go see for himself. Luke tells him that they "weren't that close," and that he hates hospitals. Tim walks away angry. Later, Luke hands Tim a card to give to Shane. Tim tells Luke to give Shane the card himself. Tim tells Luke that if he had stayed with Shane that night, he probably wouldn't be in the hospital. Luke yells that he already knows that and feels guilty about it and walks away. Tim picks up Luke's card off the ground.
In Bye-Bye Junior High, Luke brings a disabled Shane to the end of the year dance.
In Nobody's Perfect, Mr. Walfish pairs Luke and Kathleen up for a Shakespeare recitation of Romeo and Juliet for English class. Luke doesn't want to bother rehearsing, but Kathleen convinces him to stay after school and practice. Kathleen's abusive boyfriend, Scott, finds them and kicks Luke out of the room.
In Little White Lies, Melanie invites the whole class to her party, including Luke, whom she has a crush on. Diana tags along with Luke and Yick when they go outside to smoke at school. They all get in trouble when Ms. Avery catches them. Melanie is disappointed when Luke doesn't show at her party. Arthur tells her that he and Yick are home playing video games.
In All In a Good Cause, Arthur feels left out when his best friend Yick is always ignoring him to hang out with Luke. Luke teases Arthur for being too straight-laced and nerdy and Yick laughs along. At the end of the episode, Luke is impressed when Arthur and Yick toilet-paper Mr. Raditch's house.
He doesn't get any main roles in season 5 either. He invited Yick, Joey and, expecting he'd be bad, Arthur to his house to play poker all night.