William "Billy" Hoskins II (aka "Super Diaper Baby") is a superhero created by George and Harold. He is an African-American baby superhero who has the exact same powers as Captain Underpants, including flight, quick learning-to-read, and better vision. Unlike most babies, Billy could talk non-gibberish directly, probably because of his then-new superpowers. But prefers to speak gibberish anyway.
Billy was born to Bill and Mary Hoskins at Saint Wendy's Hospital. Dr. Stanley Stanburg decided to give Billy the "Spank of Life," a tradition done to all babies who didn't cry at birth, and spanked him so hard he flew out of the doctor's hand and out the window. Meanwhile, Deputy Dangerous was riding by on. Diaper Dog, and Billy fell into the cup. It is shown Billy fell out of the seventh story. Anyway, Billy's impact it the cup caused the deputy and his dog to fall, while Billy drank the Superhero Juice, therefore gained superpowers. Deputy then started yelling at Billy and told him to "give them to me NOW!!!" causing Billy to punch him in the face, jump on his head, and grab his nose and flinging his body up and down against the ground.
The Adventures Of Super Diaper Baby
Newborn Baby, Billy Hoskins gains super powers to defeat the vengeful villain, Deputy Dangerous, who transforms into a giant piece of poo, but not without his best friend Diaper Dog by his side. Billy is the Main Protagonist of the book.
The All New Captain Underpants Extra-Crunchy Book O' Fun 2
Super Diaper Baby and Diaper Dog help Captain Underpants defeat Hairy Potty and his bride in the comic section of the activity book.
Captain Underpants And The Big Bad Battle of the Bionic Booger Boy Part 1: Night Of the Nasty Nostril Nuggets
Diaper Dog and Super Diaper Baby make a cameo in Gorge and Harolds comic book, "Captain Underpants And The Terrifying Tale of the Tattle-Tron 2000", going to Baby Jail and Dog Jail. They appear once again going out the jails at the end of the comic book.
Super Diaper Baby 2: The Invasion Of The Potty Snatchers
Billy and Diaper Dog must put an end to Petey and Rip Van Tinkle' s toilet stealing plans and save the town for the second time.
- Super Diaper Baby calls Diaper Dog, Doggy all the time.
- Billy was called Super Diaper Baby by other characters only once in the first book.
- Billy was named after his weak, scared cat Father, Bill.
- Billy is shown to have laser eyes on the online game, but he doesn't use them in his books.
- Super Diaper Baby's favorite drink is a Juice Box.
- Billy Hoskins can speak fluently due to his powers.