Sebastian Horsley (born August 8, 1962) is a London artist best known for having undergone a voluntary crucifixion. Horsley's writings often revolve around his dysfunctional family, his drug addictions, sex, and his reliance on prostitutes.
Horsley is the elder son of Nicholas Horsley, the millionaire chairman of Northern Foods, which had been founded by Nicholas's father. His mother, the former Valerie Edwards, was a Welsh typist. After his parents' divorce, Horsley's father married Sabitha Sarkar (married 1975-1987) and Alwyne Law (married 1998). His mother did not remarry but later became known as Valerie Walmsley-Hunter.
Both of his parents were alcoholics and indulged in numerous affairs before divorcing in 1975. As Horsley wrote in his memoirs, "Clearly everyone in my life who should have been vertical was horizontal". In an interview she gave to the Sunday Times, Horsley's mother admits that her son's childhood was profoundly difficult, saying, "I don't think Nicholas ever went to bed sober and I was always in a fog. Sebastian and my other two children were accidents and, though it seems shocking to admit, I drank all the way through my pregnancies." Still, she added, "I tried not to be drunk when the kids came home from school ..." 
In 1983, Horsley married Evlynn Smith (born Evelynn Anne Smith), who was the daughter of a Scottish painter and decorator, and who together with Meriel Scott constituted the art and furniture-design company Precious McBane. Horsley and Smith separated in 1990 and Smith died of an aneurysm in 2003, at age 40.
In August 2000 Horsley traveled to the Philippines to experience a crucifixion, in order to prepare for a series of paintings on the topic. Refusing pain killers, he was nailed to a cross and passed out. The foot rest broke and he fell off. A film and photos of the event, as well as his subsequent paintings of crosses, were exhibited in London in 2002.
In an editorial article in The Observer in 2004, he described his preference for sex with prostitutes, writing "What I hate with women generally is the intimacy, the invasion of my innermost space, the slow strangulation of my art." He also stated that he himself had worked as a prostitute for a while. He argued that prostitution should not be legalized, as that would take away part of its thrill.
Horsley ran a monthly column in the Erotic Review from 1998 to 2004. In early 2006, Horsley together with Marion McBride began to run a weekly sex advice column in The Observer. Four months later, after graphic discussions of oral and anal sex had led to numerous complaints from readers, the column was discontinued.
In September 2007, the Spectrum London gallery staged Hookers, Dealers, Tailors, a retrospective by Horsley. The show documented his diving in Australian shark-infested water and copiously ingesting deadly drugs.
His memoir, Dandy in the Underworld (ISBN 1841157546), named after the T.Rex album of same name (Horsley counts Marc Bolan as one of his idols) was published in the UK by Sceptre in September 2007 and in the USA in March 2008 from Harper Perennial. In it, he claims to have had an affair with the Scottish gangster-turned-artist Jimmy Boyle. Horsley further stated that his late wife, Evlynn, also had an affair with Boyle, who served as best man at the couple's wedding, according to Horsley's mother.
Horsley was refused entry into the United States March 19, 2008, after arriving at Newark Airport for a book tour. Immigration officers denied his entry claiming issues of moral turpitude. "...travelers who have been convicted of a crime involving moral turpitude (which includes controlled-substance violations) or admit to previously having a drug addiction are not admissible..." said customs spokeswoman, Lucille Cirillo. After eight hours of questioning, he was placed on a plane and sent back to London. Horsley had told the Associated Press that he had prepared for the visit; his one concession: removing his nail polish.