John Winston Ono Lennon (born John Winston Lennon; 9 October 1940 – 8 December 1980) was an English musician and activist. He gained global fame as the founder, co-lead vocalist and rhythm guitarist of the Beatles. Lennon's songwriting partnership with Paul McCartney remains the most successful in history.

Born in Liverpool, Lennon became involved in the skiffle craze as a teenager. In 1956, he formed the Quarrymen, which evolved into the Beatles in 1960. He initially was the group's de facto leader, a role he gradually seemed to cede to McCartney, writing and co-writing songs with increasing innovation, including "Strawberry Fields Forever", which he later cited as his finest work with the band. Lennon soon expanded his work into other media by participating in numerous films, including How I Won the War (1967), and authoring In His Own Write (1964) and A Spaniard in the Works (1965), both collections of nonsense writings and line drawings. Starting with "All You Need Is Love", his songs were adopted as anthems by the anti-war movement and the counterculture of the 1960s.

In 1969, he started the Plastic Ono Band with his second wife, multimedia artist Yoko Ono, held the two-week-long anti-war demonstration bed-in for peace, and left the Beatles to embark on a solo career. Lennon and Ono collaborated on many works, including a trilogy of avant-garde albums and several more films. After the Beatles disbanded, Lennon released his solo debut John Lennon/Plastic Ono Band and the international top-10 singles "Give Peace a Chance", "Instant Karma!", "Imagine", and "Happy Xmas (War Is Over)". Moving to New York City in 1971, his criticism of the Vietnam War resulted in a three-year deportation attempt by the Nixon administration. Lennon and Ono separated from 1973 to 1975, during which time he produced Harry Nilsson's album Pussy Cats. He also had chart-topping collaborations with Elton John ("Whatever Gets You thru the Night") and David Bowie ("Fame"). Following a five-year hiatus, Lennon returned to music in 1980 with the Ono collaboration Double Fantasy. He was shot and killed by Mark David Chapman, three weeks after the album's release.

As a performer, writer or co-writer, Lennon had 25 number-one singles in the Billboard Hot 100 chart. Double Fantasy, his second-best-selling non-Beatles album, won the 1981 Grammy Award for Album of the Year. That year, he won the Brit Award for Outstanding Contribution to Music. In 2002, Lennon was voted eighth in a BBC history poll of the 100 Greatest Britons. Rolling Stone ranked him the fifth-greatest singer and 38th-greatest artist of all time. He was inducted into the Songwriters Hall of Fame (in 1997) and the Rock and Roll Hall of Fame (twice, as a member of the Beatles in 1988 and as a solo artist in 1994).

John Winston Lennon was born on 9 October 1940 at Liverpool Maternity Hospital, the only child of Alfred and Julia Lennon (née Stanley). Alfred was a merchant seaman of Irish descent who was away at the time of his son's birth. His parents named him John Winston Lennon after his paternal grandfather, John "Jack" Lennon, and Prime Minister Winston Churchill. His father was often away from home but sent regular pay cheques to 9 Newcastle Road, Liverpool, where Lennon lived with his mother; the cheques stopped when he went absent without leave in February 1944. When he eventually came home six months later, he offered to look after the family, but Julia, by then pregnant with another man's child, rejected the idea. After her sister Mimi complained to Liverpool's Social Services twice, Julia gave her custody of Lennon.

In July 1946, Lennon's father visited her and took his son to Blackpool, secretly intending to emigrate to New Zealand with him. Julia followed them – with her partner at the time, Bobby Dykins – and after a heated argument, his father forced the five-year-old to choose between them. In one account of this incident, Lennon twice chose his father, but as his mother walked away, he began to cry and followed her. According to author Mark Lewisohn, however, Lennon's parents agreed that Julia should take him and give him a home. Billy Hall, who witnessed the incident, has said that the dramatic portrayal of a young John Lennon being forced to make a decision between his parents is inaccurate. Lennon had no further contact with Alf for close to 20 years.

Throughout the rest of his childhood and adolescence, Lennon lived at Mendips, 251 Menlove Avenue, Woolton, with Mimi and her husband George Toogood Smith, who had no children of their own. His aunt purchased volumes of short stories for him, and his uncle, a dairyman at his family's farm, bought him a mouth organ and engaged him in solving crossword puzzles. Julia visited Mendips on a regular basis, and John often visited her at 1 Blomfield Road, Liverpool, where she played him Elvis Presley records, taught him the banjo, and showed him how to play "Ain't That a Shame" by Fats Domino. In September 1980, Lennon commented about his family and his rebellious nature:

A part of me would like to be accepted by all facets of society and not be this loudmouthed lunatic poet/musician. But I cannot be what I am not [...] I was the one who all the other boys' parents – including Paul's father – would say, "Keep away from him" [...] The parents instinctively recognised I was a troublemaker, meaning I did not conform and I would influence their children, which I did. I did my best to disrupt every friend's home [...] Partly out of envy that I didn't have this so-called home [...] but I did [...] There were five women that were my family. Five strong, intelligent, beautiful women, five sisters. One happened to be my mother. [She] just couldn't deal with life. She was the youngest and she had a husband who ran away to sea and the war was on and she couldn't cope with me, and I ended up living with her elder sister. Now those women were fantastic [...] And that was my first feminist education [...] I would infiltrate the other boys' minds. I could say, "Parents are not gods because I don't live with mine and, therefore, I know."