William is one of Cory's best friends. He is known to be very smart, and loves ducks. He is afraid of girls, and he can play the clarinet and keyboard. His classmates call him "Captain Brainypants". He "invents" many different gadgets in various episodes, such as the "remote-controlled refrigerator opener". He once does Raven's science project, in exchange for her designing him a new wardrobe to look "cooler". It has been implied that William is younger than Cory, but it is not known how much younger.