Thad Jarvis is a kid who is an expert guitar player. His favourite video game is a Guitar Hero. In the "Guitar Queer-o" episode, he tried to score million points in the Guitar Hero game with Stan Marsh. He quits when Stan becomes a euphemism of a rock star with addictions to the game Heroin Hero and being a crabby jerk. One of his notable feats is playing two songs (one of which is John the Fisherman) on the controller without the game so well that other people can hear him and compliment him on his skills. Thad has curly brown, wavy hair, which falls over his eye. His mouth is high up on his face. He wears a black shirt, and jeans. The most notable appearance of Thad is that his head is always looking up.

Another thing majority of people don't know is that he also appears in the season 10 episode, Smug Alert! He is one of the stoner kids who Kyle Brofloski meets when he moves to San Francisco.