Friend and journalist Andrew Richardson said Monday that Postlethwaite died in a hospital Sunday.
The actor was instantly recognizable for his unusually shaped face - with prominent cheekbones that gave him a lean, rugged look - and his intense eyes. He was not conventionally handsome like many film stars but had a powerful presence and authenticity on screen and on stage.
His extended battle against cancer was well documented in the local newspapers where he lived in rural Shropshire, 170 miles northwest of London. He had recently thanked the staff at the Royal Shrewsbury Hospital for their kind treatment and care.
"They have been wonderful and I am grateful to them," he told the Shropshire Star newspaper. "I cannot thank them enough for everything that they have done for me."
Postlethwaite originally wanted to be a priest but was drawn to acting despite his father's objections about the insecurity of a career in show business. He worked first as a drama teacher before striking out on his own.
Like many English actors, he started his career on stage, performing at the Everyman Theatre in Liverpool and working with the Royal Shakespeare Company.
He branched out into movies and television work in the 1980s, most often taking roles as an occasionally menacing working-class figure.
He reached what some viewed as his professional peak when he received a best supporting actor Oscar nomination for his role in "In the Name of the Father", a film starring Daniel Day-Lewis and Emma Thompson. Postlethwaite played Day-Lewis' father in the drama about the complex ramifications of Day-Lewis' forced confession to an IRA bombing he didn't commit.
He had recently been seen in the critically acclaimed film "Inception" and had worked with Spielberg on "The Lost World: Jurassic Park" and "Amistad" in performances that sparked the extravagant compliment from Spielberg, a longtime admirer.
Despite the plaudits, and the steady flow of quality roles, Postlethwaite never fully embraced the Hollywood star culture and kept a good distance between himself and the film colony.
Friends and colleagues described him as honest and down-to-earth in a profession filled with big egos.
"Anyone who worked with him felt great affection for him," actor David Schneider told BBC News. "He was very un-actory. Sort of like a national treasure. There is so much affection for him, a wonderful actor and a wonderful bloke."
Postlethwaite liked the rural life, spending his final years in rural England while remaining active in films and on stage. He recently made a triumphant return to the Everyman Theatre in Liverpool to star as King Lear.
Postlethwaite did not become a household name in much of the world - he is said to have resisted an agent's efforts to come up with a stage name that would be easier to pronounce and remember - but he was honored by Queen Elizabeth II when he received an OBE award in 2004.
He was a political activist known for his opposition to the war in Iraq and his calls for policies to fight global warming. He used a wind turbine at his home to generate electricity and made other "green" alterations to the property.
He is survived by his wife, Jacqui, his son Will and daughter, Lily.
