Fidel Castro is a supposed communist. He's reported to have been opposed to America and leaded Cuba with an iron fist. He came to power the good old fashioned way, a revolution. He was one of the major players during the Cold War and a valuable ally to the Soviets. It's because of him that the United States government decided to make cuban cigars illegal. The CIA and other Country Departments have tried many times to kill him through assassination attempts including the famed "Operation 40" but all have failed.
Troubled health led him to resign from the presidency and hand over rule of Cuba to has his brother Raul.
Castro appears in the mission Operation 40, where Mason, Woods and Bowman 's mission is to assassinate Fidel Castro. Mason successfully kills a double who they believed to be Castro, but it is later revealed in the same mission by Castro himself that Mason killed a double. When trying to escape in an airplane from Cuba, they are faced by a blockade and Mason is forced to jump off to help cover the escape of the rest of the Op 40 members on the mission, the real Castro then captures Mason, and turns him over to Nikita Dragovich as a "gift" at the Rusalka.