Jack Lemmon, the brash young American Everyman who evolved into the screen's grumpiest old Everyman during a movie career that lasted a half century, died on Wednesday at a hospital in Los Angeles. He was 76 and lived in Beverly Hills.

The cause was complications from cancer, said a spokesman, Warren Cowan.

Through most of his more than 60 movies, Mr. Lemmon was the least glamorous and most approachable of movie stars -- the good-natured, ordinary guy next door with a slightly skewed moral compass. He was a master of sardonic comedy and could convey urban frustrations so deftly that audiences identified with him and thus were able to laugh at themselves.

As C. C. Baxter in "The Apartment" (1960), Billy Wilder's Academy Award-winning film, he created the definitive comic hero for an age of anxiety, a salaryman so eager to win a promotion that he lends his apartment to his married bosses for weekly trysts with their secretaries. As a lecherous landlord in "Under the Yum Yum Tree" (1963), he rented apartments only to pretty and, he hoped, compliant women.

As Ensign Pulver in "Mister Roberts" (1955), a performance that gained him an Oscar for best supporting actor, he was a callow but likable wheeler-dealer. As a policeman turned pimp in Mr. Wilder's "Irma la Douce" (1963), he was so bewitched by a prostitute that he tricked her by becoming her lover in disguise. And in one of his most memorable roles, as a musician forced to dress up as a woman to escape gangsters in Mr. Wilder's "Some Like It Hot" (1959), he got engaged to another man (played by Joe E. Brown) because it was his only chance to marry a millionaire.

"Some Like It Hot" ended with a classic last line. When Mr. Lemmon, as Daphne, finally tells the millionaire that he is a man, Brown's response is, "Nobody's perfect."

Roles that would have been distasteful in the hands of another actor were redeemed by Mr. Lemmon's keen and agile clowning, bedrock affability, cherubic face and jaunty smile. The critic Pauline Kael found him "demoniacally funny" in "Some Like It Hot," while Stanley Kauffmann described him as "easily one of the most expert American actors of his generation."

But Mr. Lemmon did not settle for simply being a skillful clown. In 1962, after making 15 comedies, one western and one adventure film during his first eight years in Hollywood, he sought out the role of a young alcoholic husband in Blake Edwards's "Days of Wine and Roses."

"The movie people put a label attached to your big toe -- 'light comedy' -- and that's the only way they think of you," Mr. Lemmon said in a 1984 interview.

"I knew damn well I could play drama. Things changed following 'Days of Wine and Roses.' That was as important a film as I've ever done."

Things changed even more in 1973 when Mr. Lemmon took home another Academy Award, this time for best actor, for his performance as a desperate garment manufacturer who hires someone to torch his warehouse in "Save the Tiger." The actor had been so eager to get the movie made that he relinquished his usual large salary and worked for scale, then $165 a week, after studio executives limited the film's budget to $1 million.

" 'Save the Tiger' cemented it," Mr. Lemmon said of Hollywood's willingness to let him move from comedy to drama and back again.

With his Oscar for "Save the Tiger," Mr. Lemmon became the first actor to win Academy Awards in both the supporting and star categories.

(One actress, Helen Hayes, had hit a similar double three years earlier when her supporting actress award for "Airport" joined her 1932 Oscar as best actress for "The Sin of Madelon Claudet.")

Mr. Lemmon also received six additional Academy Award nominations -- for "Some Like It Hot"; "The Apartment"; "Days of Wine and Roses"; "The China Syndrome" (1979), as a manager of a nuclear power plant who is shattered by his discovery that a nuclear accident was covered up; "Tribute"(1980), repeating his stage role as a Broadway press agent dying of leukemia; and Costa-Gavras's "Missing" (1982), as a conservative father whose trust in the United State government is destroyed when he journeys to South America to discover the truth about the disappearance of his politically radical son.

Mr. Lemmon was showered with acting prizes, among them the American Film Institute's life achievement award, the first Harvard Arts Medal, Kennedy Center Honors, a Lincoln Center Film Society tribute, the Screen Actors Guild life achievement award and Cannes International Film Festival awards as best actor for his political films "The China Syndrome" and "Missing."

From 1959 to 1972 Mr. Lemmon was to Billy Wilder what Clint Eastwood was to Don Siegel and what Marcello Mastroianni was to Fellini -- the perfect actor to express a director's vision. Mr. Wilder, who wrote and directed seven films with Mr. Lemmon, once said: "Jack Lemmon is a ham. And you can always trim a ham. Jack Lemmon always gives you everything."

Shirley MacLaine, who starred with Mr. Lemmon in Mr. Wilder's "Apartment" and "Irma la Douce," described the director's relationship with the actor as a "professional infatuation" and remembered standing around while Mr. Wilder did extra takes of a scene just to see what new things Mr. Lemmon would come up with.

In a second classic collaboration, Mr. Lemmon starred with Walter Matthau in 10 movies, many of them directed by Mr. Wilder. Their first pairing, in 1966, was "The Fortune Cookie," their last "The Odd Couple II" in 1998. Mr. Matthau died almost exactly a year ago, on July 1, at 79.

Mr. Lemmon almost always played the timid, neurotic schnook to Mr. Matthau's tricky whirlwind.

He was Stan Laurel to Mr. Matthau's blustering Oliver Hardy and Bob Hope to Mr. Matthau's smoothly conniving Bing Crosby: the patsy who goes along with a plot to defraud an insurance company hatched by Mr. Matthau's outrageous brother-in-law in "Fortune Cookie"; the star reporter who has no chance against Mr. Matthau's unscrupulous, egomaniacal newspaper editor in Mr. Wilder's remake of "The Front Page" (1974); the suicidal, neat freak Felix who is rescued by Mr. Matthau's slob of an Oscar in Neil Simon's "Odd Couple" (1968).

Mr. Matthau, the son of immigrants, grew up in poverty on the Lower East Side of Manhattan.

Mr. Lemmon was a child of privilege who was destined for Harvard. Jack Lemmon, Mr. Matthau once said, "is a clean-cut, well-scrubbed Boston choirboy with quiet hysteria seeping out of every pore."

They were friends in real as well as reel life. Mr. Matthau starred in the one film that Mr. Lemmon directed, "Kotch" (1971), and Mr. Lemmon acted in "The Grass Harp" (1995), the first film directed by Charles Matthau, Mr. Matthau's son.

Both men always insisted that during their 40 years of friendship, they never had a single argument.

Mr. Lemmon was also a perfect actor for bringing Mr. Simon's neurotic characters to the screen, among them the fastidious hypochondriac Felix in "The Odd Couple"; the hysterical visitor to New York in "The Out-of-Towners"(1970); and the jobless paranoid in "The Prisoner of Second Avenue" (1974).

John Uhler Lemmon 3rd was born on Feb. 8, 1925, to a life-of-the-party mother and a father who was an executive with the Doughnut Corporation of America and an amateur soft-shoe dancer.

An only child, he was cherished, and sent to the best private schools in Boston. Later he was made an unwilling witness to the disintegration of his parents' marriage.

His fun-and-games facade and clownish cheerfulness, he acknowledged, were his way of coping with the complexity of his parents' relationship.

His mother, who spent most of her nights in the bar of the Ritz-Carlton Hotel in Boston, twice gave the hotel a $400 check so that an urn containing her ashes could be kept behind the bar when the appropriate moment came for a toast to her memory.

Both times the hotel returned the money.

From Ivy League to Piano Bar

Educated at Rivers Country Day School and Phillips Andover Academy, where he was a track star, Mr. Lemmon fell in love with the piano at age 14 and taught himself to play by ear. By the time he entered Harvard in 1943 acting had become his second love. An indifferent student, he was chosen president of the university's musical-comedy group, the Hasty Pudding Club, and vice president of the Dramatic and Delphic clubs.

Despite low marks in the Reserve Officers Training Corps at Harvard, he was commissioned as an ensign during the last days of World War II and spent seven months in the Navy without seeing action. (He would draw on this experience when he played the irrepressible Ensign Pulver in "Mister Roberts.")

He returned to Harvard in 1946 and graduated in 1947. Borrowing $300 from his father, Mr. Lemmon went to New York to act.

For more than a year, most of his earnings came from playing piano at the Old Knick bar on Second Avenue.

When his father visited his son's fifth-floor walk-up apartment, all John Lemmon managed to say was, "Harvard! For this?"

Eventually, the young actor began getting roles on radio soap operas and live television dramas. He wanted to be a stage actor and made his Off Broadway debut in 1947 as the star of Tolstoy's "Power of Darkness," directed by Uta Hagen. But television paid the bills. He appeared in more than 400 live television roles and was a familiar face on the leading dramatic shows of the period, among them the anthology series "Robert Montgomery Presents," "Danger," "The Goodyear TV Playhouse," "Kraft Television Theater," "Studio One" and "Suspense."

He met Cynthia Stone when she played opposite him in "The Power of Darkness." They played opposite each other again in a short-lived television sitcom, "That Wonderful Guy," and married in May 1950, after the series was canceled.

As newlyweds they starred as newlyweds in another short-lived sitcom, "Heaven for Betsy," and in "Size 12 Tantrum" on "Newsstand Theater," an anthology series that lasted four weeks.

Mr. Lemmon thought his stage career was finally getting under way when he won the role of the harassed playwright in a 1953 Broadway revival of the 1937 farce "Room Service" Instead, a talent scout for Columbia Pictures, Max Arnow, who had noticed the actor two months earlier in "Dinah, Kip and Mr. Barlow" on "Robert Montgomery Presents" plucked him for Hollywood.

He was handed the role of the boyfriend of Judy Holliday's character in "It Should Happen to You" (1954).

He made another hit comedy with Judy Holliday the same year called "Phffft!" "Mister Roberts," directed by John Ford and Mervyn LeRoy, was Mr. Lemmon's fourth film. Master of Screen or Stage

Unusual among movie actors who were not previously well-known stage actors, Mr. Lemmon began returning to the stage as early as 1960, when he played an idealistic lawyer in "Face of a Hero" on Broadway.

"People think I'm an idiot to do this play, to leave Hollywood when I'm so hot," Mr. Lemmon told The New York Times Magazine.

"But after eight years of doing a few minutes of film a day, I wanted the satisfaction of really working and building on a scene. If this play bombed, I'd do it again tomorrow."

The play did bomb, and Mr. Lemmon returned to the stage in Los Angeles and New York. In 1978 he earned the praise of Walter Kerr, a theater critic for The New York Times, who admired the way the actor seemed to think with his entire body, and a Tony nomination as the dying press agent in "Tribute," which ran for 212 performances despite the play's lack of critical acclaim.

In 1986 he tackled "Long Day's Journey Into Night." While he prepared to play James Tyrone, the father in Eugene O'Neill's searing disintegration of a family, Mr. Lemmon, a friendly but private man, began talking about his relationship with his mother, who had been addicted to alcohol and sleeping pills.

"She was never gone to the extent of Mary Tyrone, thank God," he told The Times.

But, "knowing her in some peculiar way helped me, even unconsciously, to understand what James Tyrone feels about Mary."

When the play opened, Kerr wrote in The Times: "It's a pleasure to report that Mr. Lemmon, a wonderful comic actor who turned to mush in the serious roles that followed the lachrymose 'Save the Tiger,' is highly disciplined here." He added that the one deficit of Mr. Lemmon's performance as O'Neill's matinee idol turned "stinking old miser" was that "this star still can't quite bring himself to let an audience hate him."

During the 1980's some movie critics began complaining that Mr. Lemmon's fine comic skills had disintegrated into anxious fussiness and sentimentality in such films as "Macaroni" (1985) and "Dad" (1989).

Mr. Lemmon did not deny his propensity for sentimentality.

"I'm a sucker for it," he told Film Comment.

Going Beyond Comedy

Mr. Lemmon's career took a new turn in the 1990's with critically praised ensemble roles as a crony of Jack Ruby's in Oliver Stone's "J. F. K."; as a real-estate salesman talking too fast and trying too hard in David Mamet's "Glengarry Glen Ross"; as Marcellus in Kenneth Branagh's "Hamlet"; and as a father who briefly returns to the family he deserted in Robert Altman's "Short Cuts."

Having been trained in television drama, Mr. Lemmon slipped easily back to the small screen every time big screen roles grew scarce.His last major role was on television as the dying university professor in "Tuesdays With Morrie."

In 1993, at 68, Mr. Lemmon became a major movie star again with the unexpected box-office success of "Grumpy Old Men," which teamed him with Mr. Matthau as boyhood friends who had become enemies over their love for the same woman some 40 years earlier.

"Grumpy Old Men" was followed by "Grumpier Old Men" (1995), another box-office success; "Out to Sea" (1997), which placed the grumpy old men on a cruise ship; and "The Odd Couple II."

Never scorched by scandal and rarely noticed by the gossip columns, Mr. Lemmon was passionate about golf and the piano. He received an Emmy in 1972 for hosting and playing the piano on a television tribute, "'S Wonderful, 'S Marvelous, 'S Gershwin."

Mr. Lemmon's first marriage ended in divorce in 1956. His second wife, Felicia Farr, an actress whom he married in 1962, survives him, along with their daughter, Courtney McCrea; a stepdaughter, Denise Gordon; a son from his first marriage, Christopher; and three grandchildren.

By the time Mr. Lemmon died, the boyish, bumbling guy next door of his first movies had turned into the graying, wiser but still spry guy across the street in his last movies.

"People are probably correct when they see me as the so-called Everyman," Mr. Lemmon said in 1996.

"I'm attracted primarily to contemporary characters. I understand them and their frustrations."

Jack Lemmon (1925)