Bad Boy Bill (born William Renkosik) is a disc jockey (DJ) from Chicago, Illinois, U.S. who plays an assortment of house music.

While only in his teens, Bad Boy Bill began his DJ career in 1985 during the Chicago house music movement of the mid to late 1980s.

He worked with Mike "Hitman" Wilson and Julian "Jumpin" Perez of the WBMX DJ mixing team, known then as the Hot Mix 5. Bill's popularity grew out of DJing parties throughout the Chicago metropolitan area, as well as opening for the Hot Mix 5. Bad Boy Bill was a regular DJ on the popular house mixes on WBMX 102.7 FM in Chicago, WGCI 107.5 FM and then on the B96 96.3 FM a top pop station.

As a remixer, he landed his first Top Five Billboard Dance Chart hit at the age of 19 – Dada Nada's "Deep Love" which also featured remixes by House music legends Frankie Knuckles & David Morales, Robert Ozn and Steve Wight.

Currently, Bad Boy Bill plays music ranging from House to Electro, and is known for playing six separate turntables at once. In 1988 and 1989, he was placed within the top three at the Disco Mix Club championships.

Bad Boy Bill also made an uncredited appearance as the club DJ in the opening scene of the 1998 film Blade.