William Richard Thorpe AM (29 March 1946 – 28 February 2007) was an English-born Australian singer-songwriter, and record producer. As lead singer of his band Billy Thorpe & the Aztecs, he had success in the 1960s with "Blue Day", "Poison Ivy", "Over the Rainbow", "Sick and Tired", "Baby, Hold Me Close" and "Mashed Potato"; and in the 1970s with "Most People I Know Think That I'm Crazy". Featuring in concerts at Sunbury Pop Festivals and Myer Music Bowl in the early 1970s, the Aztecs also developed the pub rock scene and were one of the loudest groups in Australia.

Thorpe also performed as a solo artist. He relocated to America from 1976 to 1996; after moving, he released the space opera Children of the Sun, which peaked in the top 40 of the Billboard Pop Album chart in 1979. He worked with ex-Aztec Tony Barber to form a soft toy company in 1987 and co-wrote stories for The Puggle Tales and Tales from the Lost Forests. Thorpe also worked as a producer and composed music scores for TV series including War of the Worlds, Star Trek: The Next Generation, Columbo, Eight Is Enough and Hard Time on Planet Earth.

Thorpe returned to Australia in 1996 and continued as a performer and producer, additionally he wrote two autobiographies, Sex and Thugs and Rock 'n' Roll (1996) and Most People I Know (Think That I'm Crazy) (1998). According to Australian rock music historian Ian McFarlane, "Thorpie evolved from child star, beat pop sensation and cuddly pop crooner to finally emerge as the country's wildest and heaviest blues rocker. Thorpie was the unassailable monarch of Australian rock music". Thorpe was inducted into the Australian Recording Industry Association (ARIA) Hall of Fame in 1991. He died of a heart attack in February 2007 and was posthumously appointed a Member of the Order of Australia in June for his contribution to music as a musician, songwriter and producer.

Unlike multiple other Australian artists, Thorpe gained musical fame internationally in countries such as Canada and the United States. His cult following, particularly after the aforementioned sci-fi themed album Children of the Sun came out, notably involved dramatic live performances outside of Australia such as with laser light shows playing inside multiple planetariums. That release alone sold approximately half a million copies worldwide.

In 2009, Thorpe was announced as one of the Q150 Icons selected for historical commemoration by the government of Queensland, his influence being recognized during the Q150 celebrations. His musical legacy continues after his death, particularly around local areas that he frequently played within live.

Billy Thorpe was born in Manchester, England, in 1946, to Bill and Mabel Thorpe. He emigrated with his parents to Australia in 1955, arriving in Melbourne and then settling in Brisbane, Queensland. He performed as a ten-year-old under the pseudonym Little Rock Allen. Six months later, after he was heard singing and playing guitar by a television producer at the back of his parents' Brisbane store, Thorpe made regular musical appearances on Queensland television, brandishing his trademark stock whip. He toured regional venues with Reg Lindsay in 1961, and national venues with Johnny O'Keefe and with Col Joye. By 1963, as an experienced singer and musician, he decided to relocate to Sydney.

In 1963, Thorpe moved to Sydney and auditioned for a regular gig at Surf City, a popular beat music venue in the city's Kings Cross area. In 1996, Thorpe wrote his first autobiography, Sex and thugs and rock 'n' roll : a year in Kings Cross 1963–1964, on his early experiences there. His backing band was an accomplished Sydney surf instrumental group called The Aztecs, comprising Colin Baigent (drums), Val Jones (rhythm guitar), future Bee Gees guitarist Vince Melouney (aka Vince Maloney) (lead guitar, vocals), and John "Bluey" Watson (bass guitar). Before Thorpe joined, The Aztecs had released "Smoke and Stack", a surf instrumental. UK-born Tony Barber (rhythm guitar, vocals) soon replaced Jones and they were known as Billy Thorpe & the Aztecs.

In 1964, the band released their second single, "Blue Day", written by guitarist Barber, which contains the first known recording of Thorpe. US songwriters Leiber and Stoller wrote "Poison Ivy" for R&B vocal group The Coasters, but Thorpe preferred the cover version by The Rolling Stones. They decided to cover it themselves; it was produced at Festival Records and released on the independent Linda Lee label. It became their breakthrough hit when it peaked at No. 1 on the local Sydney charts. The band was signed by Ted Albert to his newly established Albert Productions, a local record label devoted exclusively to recording Australian pop artists. Billy Thorpe & the Aztecs had national chart success, their record sales and concert attendances rivalling those of The Beatles, with hits like "Mashed Potato", "Sick and Tired" and Wizard of Oz tune "Over the Rainbow" in the top ten of the record charts in most state capitals. Thorpe once said that "Mashed Potato" was inspired by a chance meeting with a schoolteacher at the Rex Hotel in Kings Cross, who was so drunk he could only mumble the words, "Mashed Potato."