A two-time victor of the Academy Award for Best Director, the "One Flew Over the Cuckoo's Nest" and "Amadeus" helmer also won three Golden Globes, the Cannes Film Festival's Grand Prize of the Jury (for "Taking Off"), the Golden Bear at Berlin ("The People vs. Larry Flynt"), a BAFTA award, and numerous other accolades.
Forman, the anti-authoritarian director who left his native Czechoslovakia for creative freedom in the U.S., was also known for two biopics - The People vs. Larry Flynt (1996) and Man on the Moon (1999).
"His departure was calm and he was surrounded the whole time by his family and his closest friends", she said.
The 1975 film, based on Ken Kesey's novel about a misfit who leads mental institution inmates in a revolt against authority, captured every major Oscar at that year's Academy Awards, the first film to do so since 1934 " s "It Happened One Night". However, it took him two years to become a United States citizen.
Forman is survived by his wife, Martina Zborilova-Forman, and four children.
His father, who had been a member of the resistance, died in the Nazi concentration camp at Buchenwald.
The Czech-born film-maker, who was 86, was one of a small number of foreign directors to enjoy lasting commercial and critical success in Hollywood.
In 1983, he made his second Oscar-winning film Amadeus, starring Tom Hulce as Wolfgang Amadeus Mozart.
"I explained I wanted to make the film because to me it was not just literature but real life, the life I lived in Czechoslovakia from my birth in 1932 until 1968", Forman told the Directors Guild of America.
The 1965 film is a bittersweet coming-of-age story that sold out in his home country before it was nominated for both an Oscar and a Golden Globe. At the time, Forman was in Paris, in negotiations for Taking Off, a USA production about the youth protest movement.
- 1958-62: Married to actress Jana Brejchova.
Forman (c.) directed Danny DeVito (l.) and Jim Carrey (r.) in the Andy Kaufman biopic "Man on the Moon". He left his second wife, singer Vera Kresadlova, behind with the couple's twin sons when he left Czechoslovakia.