Born on December 22, 1962 in Suffolk, UK, the eldest of seven children, including brother of Joseph Fiennes. He is an eighth cousin of Prince Charles.
The eldest child of Mark Fiennes (1933–2004), a farmer and photographer whose father was industrialist Sir Maurice Fiennes (1907–1994), and Jennifer Lash (1938–1993), a writer of English and Irish descent Fiennes is an eighth cousin of the Prince of Wales, and a third cousin of adventurer Ranulph Fiennes and author William Fiennes. The eldest of six children, his siblings are actor Joseph Fiennes (Shakespeare in Love, Luther, FlashForward); Martha Fiennes, a director (in her film Onegin, he played the title role); Magnus Fiennes, a composer; Sophie Fiennes, a filmmaker; and Jacob Fiennes, a conservationist. His foster brother, Michael Emery, is an archaeologist. His nephew Hero Fiennes-Tiffin played Tom Riddle, young Lord Voldemort, in Harry Potter and the Half Blood Prince.
Fiennes met English actress Alex Kingston while they were both students at the Royal Academy of Dramatic Art. After dating for ten years, they married in 1993. They divorced in 1997. In 1995, Fiennes began an affair with Francesca Annis, whom he met when she played his mother Gertrude in the play Hamlet. After 11 years together, the couple separated in February 2006. Fiennes had been reported as being romantically involved with Lady Amanda Harlech.