William is one of Cory's best friends. He is a lot smaller and nerdier than Cory, but their friendship persists despite all odds. They were also in a band together with their friend Larry.
William is extremely nerdy and intelligent. He is disliked by the other kids, who call him names and bully him in other ways. However, he and Cory are good friends. This possibly has to do with the fact that William's intelligence can easily cause great monetary gain for Cory. He is good at chemistry and afraid of girls (as he believes they make his mouth dry). He plays the flute in Cory's band, although it is changed to a keyboard later in the series. He usually goes along with Cory's schemes and does whatever he says. He loves rubber ducks, which is why he wears a shirt with a rubber duck design on it (later changed to a jacket with the rubber ducks on the inside). Although William is very weak and not the least bit brave, he is a good friend to Cory nonetheless.