James Fox is the second of three sons, born to the theatrical agent Robin Fox and his actress wife Angela Worthington - aka Angela Fox. His brothers are the actor Edward Fox and the producer Robert Fox. He started acting as a child actor and used his real name, until he reached his early 20s. He trained at the Central School of Speech and Drama. He left for nine years from 1970 to 1979 to pursue Christian vocational work. His niece is the actress Emilia Fox and he has a half-brother to the actor Daniel Chatto. From his marriage to Mary Piper, he has four sons: Thomas Fox, born 1975; Robin Fox, born 1976; the actor Laurence Fox, born 1978; 'Jack Fox, born 1985 and one daughter, Lydia Fox, born 1979. He published a book, "Comeback: An Actor's Direction", in 1983.

Brother of Edward Fox.

Son of Angela Fox.

Father of Laurence Fox.

Uncle of actress Emilia Fox.

Had a relationship with the actress Sarah Miles in the early 1960s.

Brother of producer Robert Fox.

Fox left the acting profession for nine years (1970-79) after he filmed Performance (1970) with Mick Jagger. A combination of his father's recent death, the strain of filming and smoking the hallucinogen DMT with Mick Jagger led to a nervous breakdown. Fox subsequently joined a religious cult known as "The Navigators".

His Patriot Games (1992) cast mate, Richard Harris, is also his niece's father-in-law.

He replaced actor John Woods in the Old Vic's early 2006 production of the Arthur Miller play "Resurrection Blues", which was directed by Robert Altman in his London theatrical debut, one month before previews began. The play was widely panned by critics, partly due to the divergent acting styles of the eclectic cast assembled by Robert Altman, which included the Swiss actor Maximilian Schell as Fox's character's cousin.