Question: Ralph Steadman is best known for his illustrations in Fear and Loathing in Las Vegas written by which American author?
Context: Fear and Loathing in Las Vegas is a 1998 American black comedy road film adapted from Hunter S. Thompson's novel of the same name.  It was co-written and directed by Terry Gilliam, starring Johnny Depp as Raoul Duke and Benicio del Toro as Dr. Gonzo.  The two embark on an initially assigned journey with journalistic purpose which turns out to be an exploration of the Las Vegas setting under the effect of psychoactive substances. GONZO: Photographs By Hunter S. Thompson is a limited-edition 224 page visual biography of photographs taken by, or of, Hunter S. Thompson, published in late 2006 by AMMO Books.  Thompson's snapshots were a combination of the subjects he was covering, stylized self-portraits, and artistic still life photos.  The "London Observer" called the photos "astonishingly good" and that "Thompson's pictures remind us, brilliantly in every sense, of very real people, real colours".  With an introduction by Johnny Depp (a friend of Thompson, and portrayer of his author surrogate, Raoul Duke, in "Fear and Loathing in Las Vegas"), the book stands as the only authorized biography of Hunter S. Thompson ever published.  Together with AMMO publisher Steve Crist, Thompson was deeply involved in the book's creation in the final months of his life, and it was the author's final work in progress when he committed suicide in February 2005. Fear and Loathing in Las Vegas: A Savage Journey to the Heart of the American Dream is a novel by Hunter S. Thompson, illustrated by Ralph Steadman.  The book is a roman à clef, rooted in autobiographical incidents.  The story follows its protagonist, Raoul Duke, and his attorney, Dr. Gonzo, as they descend on Las Vegas to chase the American Dream through a drug-induced haze, all the while ruminating on the failure of the 1960s countercultural movement.  The work is Thompson's most famous book, and is noted for its lurid descriptions of illegal drug use and its early retrospective on the culture of the 1960s.  Its popularization of Thompson's highly subjective blend of fact and fiction has become known as gonzo journalism.  The novel first appeared as a two-part series in "Rolling Stone" magazine in 1971, was published as a book in 1972.  It was later adapted into a film of the same name in 1998 by Terry Gilliam, starring Johnny Depp and Benicio del Toro who portrayed Raoul Duke and Dr. Gonzo, respectively. The Joke's Over is a book written and illustrated by Ralph Steadman chronicling the odd and very often dangerous times when he met and worked with his friend Hunter S. Thompson.  There are some illustrations by Steadman created at the time of the events as well as photos taken by Steadman and Thompson. Troy Evans (born February 16, 1948) is an American actor who is perhaps best known for his role as Desk Clerk Francis "Frank" Martin in the television drama series "ER."  He has also appeared in the movies "Tiger Cruise" (Disney Channel original movie), "", "Under Siege", "Teen Wolf", "Kuffs", "Fear and Loathing in Las Vegas", "Black Dahlia", "Demolition Man", "The Frighteners", and "View From the Top" among others.  He voiced Thistle Jinn in the 2013 animated adventure film "Epic". Ralph Steadman (born 15 May 1936) is a Welsh artist best known for his work with American author Hunter S. Thompson. Oscar "Zeta" Acosta (April 8, 1935 – disappeared 1974) was an American attorney, politician, novelist and activist in the Chicano Movement.  He was most well known for his novels "Autobiography of a Brown Buffalo" (1972) and "The Revolt of the Cockroach People" (1973), and his friendship with American author Hunter S. Thompson.  Thompson characterized him as a heavyweight Samoan attorney, Dr. Gonzo, in his novel "Fear and Loathing in Las Vegas".  Acosta disappeared in 1974 during a trip in Mazatlan, Mexico, and is presumed dead. Kim Flowers is an American actress who is best known for her supporting roles in the films "" and "Fear and Loathing in Las Vegas" and for her supporting roles in the TV series' "" and "H.E.L.P.". Raoul Duke is the fictional character and antihero based on Hunter S. Thompson in his autobiographical novel "Fear and Loathing in Las Vegas".  The book was originally written under the name Raoul Duke. Fear, and Loathing in Las Vegas (sometimes stylized as Fear & Loathing in Las Vegas or Fear N' Loathing in Las Vegas, abbreviated as FALILV) is a Japanese
Answer: Hunter S. Thompson