With a cast led by Jack Nicholson at the height of his powers, Cuckoo's Nest emerged as a massive success, a seminal product of the New Hollywood and victor of all top five Academy awards.
"I heard from (Forman's wife) Martina Forman very early this morning letting me know Milos passed away at Danbury Hospital near his home in Warren, Connecticut", Forman's friend and agent Dennis Aspland said.
The 86-year-old director died at dwelling within the Czech Republic "surrounded the entire time by his household and his closest pals.â".
Forman, the anti-authoritarian director who left his native Czechoslovakia for creative freedom in the United States, was also known for two biopics - "The People vs. Larry Flynt" (1996) and "Man on the Moon" (1999).
Forman, a respected figure in the cinema redefined the world of film with this two films "The Loves of a Blonde" and "The Firemen's Ball" during the peak of the Czechoslovak New Wave in the 1960s.
In many ways, Cuckoo set the tone for Forman's Hollywood work to follow, a filmography dominated largely by thoughtful adaptations and biographies. He achieved global acclaim with the 1975 Cuckoo's Nest, starring Jack Nicholson and set inside a mental institution.
For his contribution to Hollywood cinema, Forman was also awarded the Directors Guild of America's (DGA) Lifetime Achievement Award in 2013 for motion picture direction.
In a 2004 interview with the LA Times, Forman said, "When we started to make our films, they were really Czech films about Czech society and Czech little people - and who cares about Czech little people?"
His father died at Buchenwald while his mother was killed in Auschwitz after both of them were accused of taking part in an anti-Nazi resistance.
Forman returned to Hair for a followup, then moved on to Ragtime, an adaptation of EL Doctorow's novel - the latter secured eight Oscar nominations (though failed to win any).
He remained connected to his birth country, filming "Amadeus" there.
"Several times before, I asked the Czech government to let my children come see me, and they never did".
The director's first marriage, to actress Jana Brejchova ended in divorce.