Mr. Klugman was already an established name in film and theatre when he was cast as the slobby sportswriter in the television sitcom "The Odd Couple." The series ran from 1970 to 1975. It was never a big ratings champion. But Mr. Klugman had a natural repartee with co-star Tony Randall, who played the fastidious culture snob Felix Unger. He won two Emmy Awards for his performance. And his work in the show became widely known when the series went into syndication. Subsequent generations grew up on repeated airings of its episodes.
The actor jumped quickly from "The Odd Couple" to "Quincy, M.E.," an hour-long drama that proved even more popular. Running from 1976 to 1983, it was a hybrid of a medical drama and a detective show, starred Mr. Klugman as a medical examiner for Los Angeles County who went beyond inspecting the body to sometimes fingering the culprit who did the victim in.
Mr. Klugman's most famous film role was as the nameless Juror No. 5 in the 1957 film version of the perennial drama Twelve Angry Men—a role star Henry Fonda, an early supporter, helped secure for him. At a critical juncture in the drama, Mr. Klugman's character, who grew up in a rough neighborhood, demonstrates to the other jurors the appropriate way to handle a switchblade. (He was the last surviving member of the movie's cast.)
That dramatic moment came naturally for Jack Klugman, who grew up in a rough-and-tumble Philadelphia, born in April 1922, the youngest of six children of Max Klugman, a house painter, and Rose, a milliner. His father died when he was only 12, and young Jack spent his time in delinquent pursuits such as pool until his sister took him to a Federal Theatre Project production of One Third of Nation.
Following his instruction, he moved to New York. After a period of struggle, he was cast in the war comedy Mr. Roberts, which starred Fonda. He acted in a 1952 Broadway revival of Odets' Golden Boy and the short-lived A Very Special Baby in 1956. But his sterling theatre credit came in 1959, when he created the role of Herbie, the soft-hearted theatre agent who pairs up with Ethel Merman's determined Rose in the musical Gypsy. The character was everything Mr. Klugman personified: urban, street smart, honest, unpretentious, good-hearted, but far from blind to the ways of the world.
In the late '60s, he got a taste of his future television life when he stepped into the role of Oscar Madison in the Broadway run of The Odd Couple.
In later years, Mr. Klugman returned to the stage, appearing in productions staged by Tony Randall's National Actors Theater, including a revival of the comedy chestnut Three Men on a Horse and a 1997 staging of Neil Simon's The Sunshine Boys.
Mr. Klugman was a heavy smoker. He once said he had taken up smoking in imitation of his idol, actor John Garfield, even going so far as to smoke like Garfield had. He was diagnosed with throat cancer in 1974. In 1989, he lost a vocal cord to cancer. It was thought he would never act again. But he returned to the stage. His voice was raspy, but affectionate audiences did not seem to mind.
He married the actress Brett Somers in 1953. They separated in 1974, but were never divorced. She frequently guest-starred on "The Odd Couple" as Oscar's ex-wife. He is survived by their two sons, Adam and David. In 2008 Mr. Klugman married his longtime partner, Peggy Crosby. She survives him as well, as do two stepsons and two grandchildren.