"Well if it isn't fat stinking billygoat Billyboy in poison."Billyboy, is a rival gang leader of Alex's complete with his own group of Droogs.
Billyboy begins the novel as a rival gang leader to Alex, similar to other groups of their age. The two groups meet in a violent clash at the Municipal Power Plant, with Alex and his Droogs leaving Billyboy's gang injured while the police arrive. At some point between Alex's arrest and release, Dim and Billyboy became police officer's. After Alex's treatment and release Billyboy is called along with Dim to the Library where Alex is being attacked by a group of elderly citizens, after unknowingly saving Alex, Dim and Billyboy take Alex outside of town to assault him before abandoning him.
Billyboy has a diminished role in the film appearing only in the earlier fight scene but not returning later as a police officer, the role being taken by Georgie.