William "Bill" Henry Cosby Jr. is a member of the Junkyard Gang, and Russell's older brother. In the Junkyard Band, he plays the drums (made from a foot-petal trashcan and a metal box) As his name suggests, he is an animated version of the series' creator, Bill Cosby (although the real Bill Cosby himself is a live-action narrator).
- Young Bill was kept in the background for the most part, giving the other kids more prominence. The real life Bill Cosby probably felt he had a large enough role as the host of the show to start with. Like Fat Albert, Bill is usually a straightforward, level headed voice of reason in the gang, although at times a little more stubborn. As the older brother of Russell, he is often trying to keep his smart-mouthed little brother out of trouble, though not always successfully. But overall his presence was pretty reduced.
- He was shown to be the biggest fan of The Brown Hornet of the group, and even played the titular hero in the gang's homemade production of a Brown Hornet episode for a contest.
- Bill is an African-American teenager based on Bill Cosby, when he was younger.
- He wears a white long-sleeve shirt, blue pants, and white sneakers with blue circles on each side.
- In the movie, Bill's shirt is now light blue with a picture of the Brown Hornet, and his shoes are now black and white.
- His appearances in the Stephen Squirrelsky and Friends' Movie Spoof Travels are AiAi the Monkey and A Day for George, The Reindeer and the Deer, Animal Story 2 (Stephen Druschke's Style), AiAi's Grand Adventure: The Search for Tails, A Cartoon Character's Life, Nikki's Adventures of Sing Along Songs Episode 7, Here Comes Winnie the Pooh, Animals, Inc. (Dragon Rockz's Style), Simba 2, Miss Bianca and the Bernard 2: Fievel's Adventure, FernGully: The Last Rainforest (Dragon Rockz's Style), A Pooh in Central Park, Bubblesrella 2: Dreams Come True, The Brave Little Piglet, Kung Fu Owen, Nikki's Adventures of Sing Along Songs Episode 8, The Thomas O'Malley Movie, Kermit Returns, Fievel the Red Nosed Mouse and The Island of Misfits, Nikki's Adventures of Sing Along Songs Episode 9, A Cartoon Character's Life Activity Center, Cloudy with a Chance of Meatballs (Justin Quintanilla's Style), Finding Alvin (J.B. Eagle's Style), Animated Tale (TheTure DisneyKing's Style), The Forest Book 2 (TrainBoy43's Style), Nikki's Adventures of Sing Along Songs Episode 10, Madagascar (FamousImagination50's Style), Sleeping Beauty (Justin Quintanilla's Style), Aurorastasia, Despicable Me (Justin Quintanilla's Style), We're Back!: A Jungle Animal's Story, Jimmynocchio, and The Wizard of Oz (Uranimated18's Style) and will even be in more movie spoof travels.