Give a stream of consciousness and then the final answer. Hoffa is a 1992 American biographical crime film directed by Danny DeVito and written by David Mamet, based on the life of Teamsters leader Jimmy Hoffa. Most of the story is told in flashbacks before ending with Hoffa's mysterious disappearance. Jack Nicholson plays Hoffa, and DeVito plays Robert Ciaro, an amalgamation of several Hoffa associates over the years. The film features John C. Reilly, Robert Prosky, Kevin Anderson, Armand Assante, and J.T. Walsh in supporting roles. The film received mixed reviews and grossed just $29 million against its $35 million budget.

Answer this question: who played jimmy hoffa in the movie hoffa?
The relevant information is: Jack Nicholson plays Hoffa, and DeVito plays Robert Ciaro, an amalgamation of several Hoffa associates over the years.
So, the final answer is Jack Nicholson.