John Mahoney, the classically trained British-born character actor who excelled at portraying working-class Americans — most famously the ex-cop father to two effete sons on the TV series "Frasier" — has died at age 77, Chicago's Steppenwolf Theatre, his longtime stage home, told NBC News on Monday.

Mahoney died of cancer Sunday in Chicago. Steppenwolf confirmed Mahoney's death, which was first reported by TMZ, and said it was canceling Monday night's performances in tribute.

"John's impact on this institution, on Chicago theatre, and the world of arts and entertainment is great and will endure," Madeline Long, a spokeswoman for the theater, said in an emailed statement. "Our hearts go out to John and his family, and to our collective Steppenwolf family."

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Mahoney was raised in Manchester, England, and studied at the storied Stretford Children's Theatre and St. Joseph's College. He moved to the United States as a young man and got his U.S. citizenship after he enlisted in the U.S. Army.

Mahoney taught English at Western Illinois University before he returned to the theater during the mid-1970s, joining the fabled Steppenwolf ensemble during summer breaks at the urging of John Malkovich, one of the company's leading actors.

"Chicago is always home," Mahoney once said, according to NBC Chicago. "No matter what, I wanted to come back to Chicago during those four months off. What better thing to do than do a play with my friends at Steppenwolf?"

By 1986, he had won a Tony Award for his role as Artie, a starstruck New York city zookeeper, in the 1986 Broadway revival of John Guare's comedy "The House of Blue Leaves."

It was just one of many plain-spoken, blue-collar characters, often from New York or Boston, whom Mahoney made his specialty, among them the aluminum-siding salesman Moe in "Tin Men"; Kid Gleason, manager of the scandal-scarred 1919 Chicago White Sox in "Eight Men Out"; and W.P Mayhew, the hard-drinking failed screenwriter in "Barton Fink."

But it was his performance as Marty Crane, the retired Seattle homicide cop in "Frasier," for which Mahoney was best remembered. He was nominated twice for Emmy awards and twice for Golden Globes for his role on the show, which ran on NBC from 1993 to 2004, during all of which his character delighted in puncturing the pomposity of his smarty-pants sons, played by Kelsey Grammer and David Hyde-Pierce.

When the show went off the air in 2004, longtime television writer Linda Holmes, now the editor of NPR's pop culture blog, Monkey See, called Mahoney "probably one of the most underappreciated elements in the cast."

"It is largely Mahoney's ability to convince the audience that he loves his neurotic sons, with whom he has nothing in common, that helps the audience overlook the fact that if you didn't know better, you'd think that Frasier and Niles were insufferable, annoying windbags," Holmes wrote for MSNBC.com.

It is with our deepest sorrow that we share the news that ensemble member of 39 years John Mahoney passed away. Tonight’s opening night performance of You Got Older has been cancelled. We are instead inviting all to gather in Front Bar this evening. All are welcome to join us. pic.twitter.com/k8yrrR7ICA — Steppenwolf Theatre (@SteppenwolfThtr) February 6, 2018

Chicago Mayor Rahm Emanuel said in a statement Monday night: "Even as his fame grew through his fantastic work in movies and television, John stayed connected to his artistic home here in Chicago in theaters and as a member of the Steppenwolf Theatre Company. Though he will be missed, his work and impact will endure for generations to come."