Bates was born at the Queen Mary Nursing Home, Darley Abbey, Derby, England, on 17 February 1934, the eldest of three boys born of Florence Mary (née Wheatcroft), a housewife and a pianist, and Harold Arthur Bates, an insurance broker and a cellist. They lived in Allestree, Derby, at the time of Bates’ birth, but briefly moved to Mickleover before returning to Allestree.

Bates’s stage debut was in 1955, in You and Your Wife, in Coventry.

In 1956 he made his West End debut as Cliff in Look Back in Anger, a role he had originated at the Royal Court and which made him a star. He also played the role on television (for the ITV Play of the Week) and on Broadway. He also was a member of the 1967 acting company at the Stratford Festival in Canada, playing the title role in Richard III.

In 1960 appeared as Giorgio in the final episode of The Four Just Men (TV series) entitled Treviso Dam.

In the later years of his life, Bates had a relationship with the Welsh actress Angharad Rees and in the last years, his companion was his longtime friend, actress Joanna Pettet, his co-star in the 1964 Broadway play Poor Richard. They divided their time between New York and London.

Bates had numerous gay relationships, including those with actor Nickolas Grace and Olympic skater John Curry as detailed in Donald Spoto’s authorized biography Otherwise Engaged: The Life of Alan Bates. Spoto characterized Bates’s sexuality as ambiguous, and said, “he loved women but enjoyed his closest relationships with men”. Even after homosexuality was partially decriminalised in Britain in 1967, Bates rigorously avoided interviews and questions about his personal life, and even denied to his male lovers that there was a homosexual component in his nature. While throughout his life Bates sought to be regarded as a ladies’ man or at least as a man who, as an actor, could appear attractive to and attracted by women, he also chose many roles with an aspect of homosexuality or bisexuality, including the role of Rupert in the 1969 film Women in Love and the role of Frank in the 1988 film We Think the World of You.

In 1969 he starred in Women in Love directed by Ken Russell with Oliver Reed and Glenda Jackson, in which Bates and Reed wrestled fully nude. He followed it appearing as Col. Vershinin in the National Theatre’s film of Three Sisters, directed by and co-starring Laurence Olivier.

Bates was married to actress Victoria Ward from 1970 until her death in 1992, although they had separated many years earlier. They had twin sons, born in November 1970, the actors Benedick Bates and Tristan Bates. Tristan died following an asthma attack in Tokyo in 1990.

Bates was made a Commander of the Order of the British Empire (CBE) in 1996, and was knighted in 2003. He was an Associate Member of RADA and was a patron of The Actors Centre, Covent Garden, London, from 1994 until his death in 2003.

In 2001 Bates joined an all-star cast in Robert Altman’s critically acclaimed period drama Gosford Park, in which he played the butler Jennings. He later played Antonius Agrippa in the 2004 TV film Spartacus, but died before it premiered. The film was dedicated to his memory and that of writer Howard Fast, who wrote the original novel that inspired the film Spartacus by Stanley Kubrick.

Bates died of pancreatic cancer in December 2003 after going into a coma. He is buried at All Saints’ Church, Bradbourne.

Donald Spoto’s 2007 book, Otherwise Engaged: The Life of Alan Bates, is a posthumous authorised biography of Alan Bates. It was written with the cooperation of his son Benedick, and includes more than one hundred interviews with people such as Michael Linnit and Rosalind Chatto.