Who plays the lead role in the film "One Flew Over the Cuckoo's Nest" which won in all five major Oscar categories in 1976?

Explanation

The 1962 novel "One Flew Over the Cuckoo's Nest" was written by the American author Ken Kesey. It was turned into a film in 1975, directed by the Czech film director Milos Forman. It became the first film since 1935 to win Awards in all five major Oscar categories. Jack Nicholson plays the lead role as McMurphy who is imprisoned for statutory rape. He pretends to be insane, however, and is tranferred to a mental institution where he is to spend the rest of his life. He makes some new friends and opposes the system and the restriction in personal rights that the staff have introduced.