Sir Athelstan Joseph Michael Eavis CBE (born 17 October 1935) is an English dairy farmer and the co-creator of the Glastonbury Festival, which takes place at his farm in Pilton, Somerset.

Eavis was born in Pilton, Somerset on 17 October 1935, and grew up at Worthy Farm in the village. His father was a dairy farmer and also a Methodist local preacher, and his mother a school teacher. Eavis was educated at Wells Cathedral School, followed by the Thames Nautical Training College in Greenhithe, Kent, after which he joined the Union-Castle Line, part of the British Merchant Navy, as a trainee midshipman. His plan was to spend twenty years at sea, and return with a pension to help subsidise the income from the family farm.

After his father died when Eavis was 19, he inherited the family farm of 150 acres (61 ha) and 60 cows. He worked at Mendip Colliery at Nettlebridge or New Rock colliery at Stratton-on-the-Fosse on the Somerset Coalfield for a couple of years to help supplement the income from the farm.

Eavis and his first wife Ruth had three children, Juliet, Rebecca and Jane, but divorced in 1964. He next married Jean Hayball, with whom he had a son, Patrick, and a daughter, Emily. Jean died of cancer in 1999, and Eavis has since married his third wife, Liz. In common with his parents and second wife, Eavis remains a practising Methodist, although he has also stated that he is "not really bothered" about the existence of God. He is a teetotaler and does not smoke.

In 1969, Eavis and his second wife Jean visited the Bath Festival of Blues. Inspired by seeing the performance of Led Zeppelin, Eavis hosted the Pilton Pop Folk & Blues Festival in 1970. The following year a free festival, Glastonbury Fayre, was organised by Andrew Kerr and associates. It later developed into Glastonbury Festival.

In 2010, the festival's 40th year, Eavis appeared on the main stage at the festival with headline artist Stevie Wonder, to sing the chorus of the latter's "Happy Birthday".

Eavis has credited a number of influences for his political views, including traditions of nonconformity in his family, as well as his time as a miner, during which he was a member of the National Union of Mineworkers. During the early 1980s he was involved in establishing a local branch of the Campaign for Nuclear Disarmament, and subsequently agreed to make the Glastonbury Festival a fundraiser for CND, as it was from 1981 to 1987.

After recovering from stomach cancer, Eavis stood as a candidate for the Labour Party in the 1997 general election in Wells, polling 10,204 votes. In 2004, however, he suggested that disillusioned Labour voters should switch their vote to the Green Party in protest at the Iraq War, though he returned to supporting the Labour Party in 2010.