William Randall Piper (born April 13, 1953) is an American rock guitarist and songwriter, best known as the co-founder and original guitarist of the heavy metal band W.A.S.P. He was also a member of Sister - later called Circus Circus, and formed the band Animal after leaving W.A.S.P.

In 1977, he met another local musician named Blackie Goozeman (later known as Blackie Lawless) at the Starwood in West Hollywood. The two became friends and began recording demos at Piper's Magnum Opus Studio. He joined Blackie's band Sister as lead guitarist with Joey Palemo (bass) and Jimi Image (drums) after the original guitarist left. Lawless later changed the name of the band to Circus Circus, allegedly after attending several performances by Ringling Bros. and Barnum & Bailey Circus.

Circus Circus evolved into W.A.S.P. by 1982. The band's live shows incorporated burning signs, mic stands made out of huge chains, and girls dancing in cages. By the end of 1985, following the release of W.A.S.P.'s second album, he decided to leave the band. He later formed the band Animal.