Terrance is a student in South Park Elementary and the son of the owner of South Park Genetic Engineering Ranch, Dr. Alphonse Mephesto. Terrance has medium-length combed brown hair and notably angry, ragged, spiky eyebrows, as well as a prominent chin. He wears a purple coat with yellow suspenders over a white shirt with a black tie, and orange pants with black socks. Terrance appears to have an abrasive personality, since he likes to actively seek out conflict despite his friendliness to some. He also appears to be incredibly arrogant and self-centered. He appears to have some sort of degree of intelligence since he’s always referred to as a straight-A student. He has two best friends, Bill and Fosse, and he plays the saxophone, he is skilled and very good at playing it.

Terrance and Kevin’s dad. A eccentric geneticist and stereotypical mad scientist.

Dr. Alphonse Mephesto’s adopted son, and Terrance’s adopted brother. Kevin is around eight years old and doesn’t speak. He just follows his dad around everywhere in the laboratory.

Bill is a student in South Park Elementary who is often seen with Fosse. Bill often laughs at silly things, due to his seeming stupidity. He also likes to annoy, especially to his best friends.

Fosse is always seen with Bill, just like what was shown. His personality is almost the same as Bill’s.