Describing some of the industry's biggest names as "overrated", "a pain in the arse" and "a stupid, stupid man", the Succession actor, 79, let rip in a new newspaper interview.
Cox made the remarks in an interview with British newspaper The Times, in which he reflected on his career and views on acting.
Speaking about Johnny Depp, Cox said he was relieved to have turned down a role in the Pirates of the Caribbean franchise, adding he felt the actor was "so overblown" and "so overrated".
He also commented on his former X2 co-star Ian McKellen, stating McKellen's acting was "not to my taste".
Cox extended his criticism to other actors, including Edward Norton, whom he described as "a pain in the arse", and Kevin Spacey, calling him "a stupid, stupid man".
Turning to directors and writers, Cox said Quentin Tarantino was "meretricious", and he had vulgar descriptions for Michael Caton-Jones and David Hare.
Discussing performances, Cox referenced Gary Oldman and his Oscar-winning portrayal of Winston Churchill in Darkest Hour.
Cox said Oldman's performance was "cobblers" and "a crowd-pleasing farrago", contrasting it with his own portrayal of Churchill in Churchill.
He also commented on casting in a new adaptation of Wuthering Heights, saying of Margot Robbie: "Margot Robbie is far too beautiful for that role."
"I mean, I think there should be something more of the Gypsy about her but it's wrong of me to judge. It may be a brilliant film," he said.
Speaking about his former Succession co-star Jeremy Strong - who went "method" on the show - Cox said: "He's a good actor, Jeremy. He's a wonderful actor. It's just all the bullshit that goes with it. You watch children - they don't say, 'What's my motivation?' They just do it!"
Cox said about how his partner begged him to watch his mouth: "I mean, my wife keeps saying, 'Brian, be careful. Brian, be careful.'
"I think, 'F*** it, I don't want to be careful any more! I'll be 80 this year ... I'm gonna say what I want to say."
11°C