William Seward Burroughs II (; February 5, 1914 – August 2, 1997) was an American writer and visual artist. Burroughs was a primary figure of the Beat Generation and a major postmodernist author whose influence is considered to have affected a range of popular culture as well as literature. Burroughs wrote eighteen novels and novellas, six collections of short stories and four collections of essays. Five books have been published of his interviews and correspondences. He also collaborated on projects and recordings with numerous performers and musicians and made many appearances in films. He was also briefly known by the pen name William Lee. Burroughs created and exhibited thousands of paintings and other visual artworks, including his celebrated 'Gunshot Paintings'.

He was born into a wealthy family in St. Louis, Missouri, grandson of the inventor and founder of the Burroughs Corporation, William Seward Burroughs I, and nephew of public relations manager Ivy Lee. Burroughs began writing essays and journals in early adolescence but did not begin publicizing his writing until his thirties. He left home in 1932 to attend Harvard University, studied English, and anthropology as a postgraduate, and later attended medical school in Vienna. In 1942 Burroughs enlisted in the U.S. Army to serve during World War II, but was turned down by the Office of Strategic Services and Navy, after which he picked up the drug addiction that affected him for the rest of his life, while working a variety of jobs. In 1943, while living in New York City, he befriended Allen Ginsberg and Jack Kerouac, and out of their mutual influence grew the foundation of the Beat Generation, which was later a defining influence on the 1960s counterculture.

Much of Burroughs' work is semiautobiographical, primarily drawn from his experiences as a heroin addict, as he lived throughout Mexico City, London, Paris and Tangier in Morocco, as well as from his travels in the South American Amazon. His work also features frequent mystical, occult or otherwise magical themes – a constant preoccupation for Burroughs, both in fiction and in real life.

Burroughs killed his second wife, Joan Vollmer, in 1951 in Mexico City. Burroughs initially claimed that he shot Vollmer while drunkenly attempting a "William Tell" stunt. He later told investigators a different story: that he had been showing his pistol to friends, when it fell and hit the table, firing the bullet that killed Vollmer. After Burroughs returned to the United States, he was convicted of manslaughter in absentia, and received a two-year suspended sentence.

Burroughs found success with his confessional first novel, Junkie (1953), but he is perhaps best known for his third novel Naked Lunch (1959), a highly controversial work that was the subject of a court case after it was challenged as being in violation of the U.S. sodomy laws. With Brion Gysin, he also popularized the literary cut-up technique in works such as The Nova Trilogy (1961–1964).

In 1983, Burroughs was elected to the American Academy and Institute of Arts and Letters, and in 1984 he was awarded the Ordre des Arts et des Lettres by France. Jack Kerouac called Burroughs the "greatest satirical writer since Jonathan Swift", a reputation he owes to his "lifelong subversion" of the moral, political, and economic systems of modern American society, articulated in often darkly humorous sardonicism. J. G. Ballard considered Burroughs to be "the most important writer to emerge since the Second World War", while Norman Mailer declared him "the only American writer who may be conceivably possessed by genius".

Burroughs created visual art throughout his lifetime, but never exhibited it until 1987, after the death of his friend and collaborator Brion Gysin. For the next and last 10 years of his life, he presented his paintings and drawings at museums and galleries worldwide.

Burroughs had one child, William S. Burroughs Jr. (1947–1981), with his second wife Joan Vollmer. William Burroughs died at his home in Lawrence, Kansas, after suffering a heart attack in 1997.