Bill and his friend Fosse McDonald are always hanging out with each other, laughing and calling things gay. They're mostly background characters, but have made a few appearances, like in Big Gay Al's Big Gay Boat Ride and Lil' Crime Stoppers.
He wears a blue shirt similar to Butters' except with a white collar and pocket. His hair is similar to Terrance Mephesto's, although it is brown and slightly shorter. He has thick eyebrows during the first four seasons, but afterward he has regular ones.
Bill is a bully, often laughing at things and people. In addition, he thinks everything is gay. Due to his seeming stupidity, it appears he did not make it to the fourth grade - he is never seen in the fourth grade classroom, but is in the halls, and is only seen in the hallway and playground after the second season. His voice appears to sound almost the same as Fosse's. He was seen again in Lil' Crime Stoppers when the boys discovered he, along with Fosse, stole Sarah Peterson's doll. He then played along and was "shot" in the game. Bill seems to be one of the more naive children in the school along with Fosse, Butters, Jason, and DogPoo Petuski. In the episode It's a Jersey Thing, he was part of Cartman's group to help capture and lock up Kyle. It seems that unlike most other kids, (Craig, Token, Jimmy) who are more aware of Cartman's manipulating methods, he still hasn't wised up to it and so that is why Cartman would most likely seek him out for help.