Bill often takes Stan's place when there are things he doesn't want to go to, such as Steve's baptism or cooking classes with Francine.
When Stan was faced with the dilemma of whether to go to the high school reunion prom with Betty Sue, the Homecoming Queen and saving his marriage with Francine in "It's Good to Be the Queen", Stan called in Bill to take Francine out to dinner while he went to the prom. But soon Francine decided to go to the prom, making things a bit complicated, since Stan decided to give up his dream rather than lose his wife. When the two of them were standing in the same gym, Francine took Stan's gun, preparing to shoot his leg. She ends up shooting the one who didn't apologize, who was actually Bill. Bill was taken aboard a helicopter, hearing that his leg can't be saved.
In "Pulling Double Booty", Hayley meets Bill after going to the CIA to having an Argument with Stan. Mistaking Bill for Stan she apologizes which leads to them getting into a relationship. When Bill is showed by Stan of how "Hot" Francine is, Bill tries to have sex with Francine by impersonating Stan. Enraged at Bill trying to hit on Francine, Stan throws Bill out of the window, by what appears to be his genitals, and tells Bill that he cannot see Hayley again. In order to stop Hayley going on a rampage when Bill dumps her, Stan pretends to be Bill to take Hayley out on a date.
Bill, like his double Stan, was voiced by Seth MacFarlane.