Mark

Mark is an unseen character in Friday the 13th: Back from the Grave.

Personality
While never appearing on screen, it is possible that he is rather obnoxious.

Pre-Pinehurst
Mark is mentioned by Crissy when she asks Kenny Riedell if he's being bothered by Mark, which Kenny declines.

George
While never seen interacting, it is possible that George doesn't like Mark.

Trivia

 * Mark, like Paul, Crissy, George, Laura, and Debbie are all based off the NES Friday the 13th game.