Oscar-nominated British actor Pete Postlethwaite has died at the age of 64, a spokesman has announced.
Journalist and friend Andrew Richardson said the actor, who was appointed OBE in 2003, died peacefully in hospital in Shropshire after a lengthy illness.
In 1994, he was nominated for an Oscar for In The Name of the Father about the IRA's Guildford pub bombings.
Former girlfriend Julie Walters praised him as "the most exciting, exhilarating actor of his generation".
The actress said Postlethwaite was a "big part" of her early acting career which they spent touring pubs together in a theatre group.
"He invented edgy. He was an exhilarating person and actor," she said.
She said she agreed with Steven Spielberg, who worked with the actor in films including The Lost World: Jurassic Park, when he described Postlethwaite as "the best actor in the world".
"I saw him in Coriolanus and it was the most terrifying, wonderful performance I have ever seen. The audience were privileged to see it," Walters added.
In The Name of the Father co-star Daniel Day-Lewis, who previously worked with Postlethwaite in repertory theatre in the 1970s, said: "Pos was the one".
"As students it was him we went to see on stage time and time again," he said of his friend.
"It was him we wanted to be like; wild and true; lion hearted; unselfconscious and deliciously irreverant. He was on our side. He watched out for us.
"We loved him and followed him like happy children, never a breath away from laughter."
Oscar-winning actor Kevin Spacey, who worked with Postlethwaite on The Usual Suspects, said "no-one was like Pete".
"He was a great man of the theatre as well and carved a unique life for himself in film. He probably wasn't appreciated as much as he should have been, but I suspect that the country will come to regard him as a national treasure," he said.
"For the rest of the world he was a guy we could all understand, empathise with and be frightened by. We will all treasure his performances and remember him with fondness and enormous admiration."
Miriam Margolyes, who featured with Postlethwaite in director Baz Luhrmann's version of Shakespeare's Romeo and Juliet, told BBC Radio 4's PM programme: "He was a dazzling actor, and he was dangerous and edgy, so that you raised your game to be with him."
Broadcaster Stephen Fry, meanwhile, wrote on Twitter: "The loss of the great Pete Postlethwaite is a very sad way to begin a year."
Actor Simon Pegg said on Twitter that Postlethwaite was "one of our finest actors", adding that he "first saw him at the RSC in 1986 - owned the stage he did".
And former deputy prime minister Lord Prescott, also writing on Twitter, said the actor's films Brassed Off and Age of Stupid "had a real effect on me and our government".
Lord Prescott has credited 1996 film Brassed Off - about the struggles faced by a colliery brass band after the closure of their pit - as the inspiration for a Labour regeneration programme for coalfield communities.
Postlethwaite's friend Mr Richardson said the actor, who also starred in films including The Usual Suspects and Baz Luhrmann's film adaptation of Romeo and Juliet, had carried on working in recent months despite receiving treatment for cancer.
He is survived by his wife and two children.
Postlethwaite, who lived near the Welsh border in Shropshire, was being treated at the Royal Shrewsbury Hospital.
He recently told the Shropshire Star that staff there had been "wonderful and I am grateful to them".
The actor, who was born in Warrington, Cheshire, began his career at Liverpool's Everyman Theatre in the 1970s, working with Walters and other future stars including Alison Steadman, Bill Nighy and Alan Bleasdale.
Nighy has paid tribute to "a rare and remarkable man".
"I was honoured by his friendship - he is irreplaceable," he added.
Postlethwaite returned to the Everyman in 2008 to play the lead in King Lear, a role he had always wanted to take on, and said afterwards the theatre had been "where I started really, or where I realised that being an actor wasn't just a flippant job".
In The Name of the Father director Jim Sheridan said Postlethwaite was "a great warrior" who "looked indestructible".
"Poss, we called him Poss, he was amazing - everybody loved him," Sheridan said.
"He took no prisoners," he added.
"Poss was wild as well - he was an amazingly virile, strong guy."
His role as Giuseppe Conlon earned him a best supporting actor Oscar nod.
To prepare for the role, Postlethwaite spent time with Conlon's son Gerry - also wrongly imprisoned as a member of the Guildford Four.
"I don't think anyone else could have played my father," Gerry Conlon told RTE Radio.
"There's times I just look at it and I think, 'Jesus, that was my dad.'
"That's how good he was."
