The actor told Shortlist that the Gonzo journalist and author was similar to 19th century author Edgar Allen Poe, who he plays in new movie The Raven.
"Hunter was very Poe," Cusack said. "I thought of him a lot during The Raven.
"I think he liked people more than Poe did. If you were friends with Hunter, you were really tight with him. But he was also someone not to be f**ked with. He could be dangerous."
He added: "He got mad at me a few times. It wasn't fun. I once bet against him on a Minnesota Vikings vs Chicago Bears [NFL] game and he lost.
"He wanted to double the bet, but I said, 'No, just pay me'. And he was like, 'You motherf**king c**ksucker!' and hung up. Then he called me later and pretended it had never happened."
> John Cusack: The Raven star's 5 essential movie roles
Watch John Cusack talk about his leading role in The Raven below: