Irwin Allen Ginsberg (/ˈɡɪnzbɜːrɡ/; 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 Lucien Carr, 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.

Best known for his poem "Howl", Ginsberg denounced what he saw as the destructive forces of capitalism and conformity in the United States. San Francisco police and US Customs seized copies of "Howl" in 1956 and a subsequent obscenity trial in 1957 attracted widespread publicity due to the poem's language and descriptions of 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, asking: "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.

For decades, Ginsberg was active in political protests across a range of issues from the Vietnam War to the war on drugs. His poem "September on Jessore Road" drew attention to refugees fleeing the 1971 Bangladeshi genocide, exemplifying what literary critic Helen Vendler described as Ginsberg's persistent opposition to "imperial politics" and the "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.

Ginsberg was born into a Jewish family in Newark, New Jersey, and grew up in nearby Paterson. He was the second son of Louis Ginsberg, also born in Newark, a schoolteacher and published poet, and the former Naomi Levy, born in Nevel (Russia) and a fervent Marxist.

As a teenager, Ginsberg began to write letters to The New York Times about political issues, such as World War II and workers' rights. He published his first poems in the Paterson Morning Call. While in high school, Ginsberg became interested in the works of Walt Whitman, inspired by his teacher's passionate reading. In 1943, Ginsberg graduated from Eastside High School and briefly attended Montclair State College before entering Columbia University on a scholarship from the Young Men's Hebrew Association of Paterson. Ginsberg intended to study law at Columbia but later changed his major to literature.

In 1945, he joined the Merchant Marine to earn money to continue his education at Columbia. While at Columbia, Ginsberg contributed to the Columbia Review literary journal, the Jester humor magazine, won the Woodberry Poetry Prize, served as president of the Philolexian Society (literary and debate group), and joined Boar's Head Society (poetry society). He was a resident of Hartley Hall, where other Beat Generation poets such as Jack Kerouac and Herbert Gold also lived. Ginsberg has stated that he considered his required freshman seminar in Great Books, taught by Lionel Trilling, to be his favorite Columbia course. In 1948, he graduated from Columbia with a B.A in English and American Literature.

According to The Poetry Foundation, Ginsberg spent several months in a mental institution after he pleaded insanity during a hearing. He was allegedly being prosecuted for harboring stolen goods in his dorm room. It was noted that the stolen property was not his, but belonged to an acquaintance. Ginsberg also took part in public readings at the Episcopal St. Mark's Church in-the-Bowery, which would later hold a memorial service for him after his death.