Martin Freeman slammed Jim Carrey for his "selfish" and "narcissistic" form of method acting in the film Man on the Moon.
The Sherlock actor, 49, was clearly not a fan of the "self-aggrandising" way Jim spent four months never breaking character for the 1999 film.
Jim refused to be called anything other than his character's name, Andy, even when the cameras stopped rolling.
Netflix documentary Jim & Andy: The Great Beyond was released in 2017 and documented the lengths Jim went to in order to stay in character.
Martin said: "For me, and I'm genuinely sure Jim Carrey is a lovely and smart person, but it was the most self-aggrandising, selfish, f***ing narcissistic b****cks I have ever seen.
"The idea anything in our culture would celebrate that or support it is deranged, literally deranged."
He continued on the Off Menu podcast : "I am a very lapsed catholic but if you believe in transubstantiation, then you're going somewhere along the line of 'I became the character' no you didn't, you're not supposed to become the f***ing character because you're supposed to be open to stuff that happens in real life because someone at some stage is going to say 'cut' and there's no point going 'what does cut mean because I'm napoleon?' Shut up."
The Hobbit actor went on to say that people "need to keep grounded in reality".
He believed that Jim's method acting was "highly amateurish" as for him it isn't a "professional attitude".
"He should have got fired," he added. "Can you imagine if he had been anybody else he would have been sectioned let alone fired, he would have been got rid of.
"It's the ridiculous leeway given to some people."
Man on the Moon is a biographical comedy-drama about Andy Kaufman, with Jim starring as the entertainer.
The film follows Andy's journey from childhood through the comedy clubs as well as television appearances that made him famous.
The movie also stars Danny Devito, Courtney Love and Paul Giamatti.
