Irwin Allen Ginsberg (; June 3, 1926 – April 5, 1997) was an American poet and writer. As a student at Columbia University in the 1940s, he began friendships with William S. Burroughs and Jack Kerouac, forming the core of the Beat Generation. He vigorously opposed militarism, economic materialism, and sexual repression, and he embodied various aspects of this counterculture with his views on drugs, sex, multiculturalism, hostility to bureaucracy, and openness to Eastern religions.

Ginsberg is best known for his poem "Howl", in which he denounced what he saw as the destructive forces of capitalism and conformity in the United States. San Francisco police and US Customs seized "Howl" in 1956, and it attracted widespread publicity in 1957 when it became the subject of an obscenity trial, as it described heterosexual and homosexual sex at a time when sodomy laws made (male) homosexual acts a crime in every state. The poem reflected Ginsberg's own sexuality and his relationships with a number of men, including Peter Orlovsky, his lifelong partner. Judge Clayton W. Horn ruled that "Howl" was not obscene, stating: "Would there be any freedom of press or speech if one must reduce his vocabulary to vapid innocuous euphemisms?"

Ginsberg was a Buddhist who extensively studied Eastern religious disciplines. He lived modestly, buying his clothing in second-hand stores and residing in apartments in New York City's East Village. One of his most influential teachers was Tibetan Buddhist Chögyam Trungpa, the founder of the Naropa Institute in Boulder, Colorado. At Trungpa's urging, Ginsberg and poet Anne Waldman started The Jack Kerouac School of Disembodied Poetics there in 1974.

Ginsberg took part in decades of political protest against everything from the Vietnam War to the War on Drugs. His poem "September on Jessore Road" called attention to the plight of Bengali refugees which was caused by the 1971 Genocide and it exemplifies what literary critic Helen Vendler described as Ginsberg's persistence in protesting against "imperial politics" and "persecution of the powerless". His collection The Fall of America shared the annual National Book Award for Poetry in 1974. In 1979, he received the National Arts Club gold medal and was inducted into the American Academy of Arts and Letters. He was a Pulitzer Prize finalist in 1995 for his book Cosmopolitan Greetings: Poems 1986–1992.