William W. Williams, who goes by Big Billy, is a supporting villain in The Powerpuff Girls and appears to be the dumbest member of the Gangreen Gang. He is very stereotypical, dimwitted and innocent. He was a major character in the episode "Slave the Day". The Powerpuff Girls don't hurt him as much except when he admits he knows he has done wrong. In the episode Schoolhouse Rocked, he is revealed to be a cyclops. He is also the only Gangreen Gang member to not have black hair. He is voiced by Jeff Glen Bennett.
Big Billy is not very bright. He often has to take direction from Ace to stay on task.
Big Billy is fat, round, has red-orange hair and has only one blue eye under his bangs as shown in Schoolhouse Rocked. He wears a big green shirt with two yellow lines on each sleeve, blue jeans, a black belt, freckles, a small dark green nose like Lil' Arturo does, only round and black and white sneakers.
Ace - Big Billy likes Ace and will do whatever he wants but sometimes Ace can get a little abusive towards Billy and push it far enough for him to lose his temper. That's when Big Billy gets mean.
The Powerpuff Girls - Big Billy actually likes The Powerpuff Girls but he still is mean to them because Ace tells him to and he is too stupid to say no.
In Demashita! Powerpuff Girls Z
Big Billy is quite different in the anime. He is not as stupid as his counterpart and he is not a cyclops. Naturally, he is very strong and can get stronger by eating. He has not the same childish nature as his counterpart. He wears a white shirt instead of the green t-shirt.
- Buttercrush (first real appearance)
- The Boys are Back in Town (non-speaking cameo when Him watches him get defeated by the girls)
- West in Pieces (as Mexican immigrants (Gang Verde), Big Billy have no lines, along with Grubber and Lil' Arturo)
- He is the only member of the Gangreen Gang who had an episode revolved around just him. Which was "Slave the Day."
- Schoolhouse Rocked and The Powerpuff Girls Rule! are only episodes where we get to see what's under Big Billy's hair. He's a Cyclops (he has only one eye.)
- In Second Chances, HIM lists his sin as "Gluttony"
- In Powerpuff Girls Z, he has both eyes, but only one is seen at a time.