James Keir Baxter (29 June 1926 – 22 October 1972) was a New Zealand poet and playwright. He was also known as an activist for the preservation of Māori culture. He is one of New Zealand's most well-known and controversial literary figures. He was a prolific writer who produced numerous poems, plays and articles in his short life, and was regarded as the preeminent writer of his generation. He suffered from alcoholism until the late 1950s. He converted to Catholicism and established a controversial commune at Jerusalem, New Zealand, in 1969. He was married to writer Jacquie Sturm.

Baxter was born in Dunedin as the second son to Archibald Baxter and Millicent Brown and grew up near Brighton, 20 km south of Dunedin city. He was named after James Keir Hardie, a founder of the British Labour Party.

Baxter's father had been a conscientious objector during World War I, and both his parents were active pacifists and socialists. His mother had studied Latin, French and German at the Presbyterian Ladies' College, Sydney, the University of Sydney and Newnham College, University of Cambridge. Baxter and his brother were not baptised, although their mother read to them sometimes from the Bible. On his first day of school at Brighton Primary School (now Big Rock Primary School), Baxter burned his hand on a stove and later used this incident to represent the failure of institutional education.

In 1936, when Baxter was ten, the family moved to Wanganui where he and his brother attended St Johns Hill School, and the following year they moved to England and attended Sibford School in the Cotswolds. Both schools were Quaker schools and boarding schools. In 1938 the family returned to New Zealand. Baxter said of his early life that he felt a gap between himself and other people, "increased considerably by the fact that I was born in New Zealand, and grew up there till I was nine, and then attended an English boarding school for a couple of years, and came back to New Zealand at thirteen, in the first flush of puberty, quite out of touch with my childhood companions and uncertain whether I was an Englishman or a New Zealander".

Baxter began writing poetry at the age of seven, and he accumulated a large body of technically accomplished work both before and during his teenage years.

In 1940, Baxter began attending King's High School, Dunedin, where he was bullied, because of his differences to other students (in personality, voice and background), his lack of interest in team sports and his family's pacifism. His older brother, Terence, was a conscientious objector like their father and was detained in military camps between 1941 and 1945 for his refusal to fight in World War II. Between 1942 and 1946, Baxter drafted around 600 poems, saying later in life that his experiences as a teenager were painful but "created a gap in which the poems were able to grow".

In 1943, Baxter's final year of high school, he wrote to a friend that he was considering becoming a lawyer, but was "not decided on it": "If I should find it possible to live by writing I would gladly do so. Yet many men have thought they could, and found it an illusion."

In March 1944, at age seventeen, Baxter enrolled at the University of Otago. That same year, he published his first collection of poetry, Beyond the Palisade, to much critical acclaim. Allen Curnow selected six poems from the collection for 1945 collection A Book of New Zealand Verse 1923–1945, and described Baxter's poems as "a new occurrence in New Zealand: strong in impulse and confident in invention, with qualities of youth in verse which we have lacked". In this year, Baxter also won the Macmillan Brown Prize for his poem "Convoys". The prize was coincidentally named after his Scottish maternal grandfather, John Macmillan Brown.