In 1970 he wrote an unconventional magazine feature entitled The Kentucky Derby Is Decadent and Depraved for Scanlan's Monthly which both raised his profile and established him as a writer with counter-culture credibility. It also set him on a path to establishing his own sub-genre of New Journalism which he called "Gonzo," which was essentially an ongoing experiment in which the writer becomes a central figure and even a participant in the events of the narrative.
Thompson remains best known for Fear and Loathing in Las Vegas (1971), a book first serialized in Rolling Stone in which he grapples with the implications of what he considered the failure of the 1960s counterculture movement. It was adapted on film twice: loosely in Where the Buffalo Roam starring Bill Murray as Thompson in 1980, and directly in 1998 by director Terry Gilliam in film starring Johnny Depp and Benicio del Toro.
Politically minded, Thompson ran unsuccessfully for sheriff of Pitkin County, Colorado in 1970 on the Freak Power ticket. He became well-known for his dislike of Richard Nixon, whom he claimed represented "that dark, venal, and incurably violent side of the American character". He covered Nixon's 1972 reelection campaign for Rolling Stone and later collected the stories in book form as Fear and Loathing on the Campaign Trail '72.
Thompson's output notably declined from the mid-1970s, as he struggled with the consequences of fame, and he complained that he could no longer merely report on events as he was too easily recognized. He was also known for his lifelong use of alcohol and illegal narcotics, his love of firearms, and his iconoclastic contempt for authoritarianism. He often remarked: "I hate to advocate drugs, alcohol, violence, or insanity to anyone, but they've always worked for me."
Thompson committed suicide at the age of 67, following a series of health problems. In accordance with his wishes, his ashes were fired out of a cannon in a ceremony funded by his friend Johnny Depp and attended by friends including then-Senator John Kerry and Jack Nicholson. Hari Kunzru wrote that "the true voice of Thompson is revealed to be that of American moralist ... one who often makes himself ugly to expose the ugliness he sees around him."