Marlon Brando (search), who turned 80 years old just two months ago, is dead, the actor's sister and a close family friend told FOXNews.com's Roger Friedman Friday morning.

Brando, often called the greatest actor of all time, is most famous for his roles in "The Godfather," "On the Waterfront," and "A Streetcar Named Desire."

Brando's sister Jocelyn exclusively confirmed the actor's death, and a family friend in Palm Springs, Calif., told FOXNews.com that Brando died Thursday at 6:20 p.m. in a Los Angeles-area hospital after being taken there Wednesday night.

"His family is gathering from all over the world and will be making arrangements following his last will and testament," said Brando's attorney David J. Seeley.

The cause of death was being withheld, Seeley said, noting the actor "was a very private man." But there were reports that Brando's death was "sudden" and he was taken to the hospital in an ambulance.

Reuters news service reported that a UCLA Medical Center (search) spokeswoman said Brando died there of lung failure.

Details about the funeral plans were not disclosed. Seeley said arrangements would be private.

His longtime friend and "Godfather" co-star James Caan (search) said he was "shocked" by the news of Brando's death. Caan said Brando "influenced more young actors of my generation than any actor.

"Anyone who denies this never understood what it was all about," Caan said.

Brando became a movie idol in the early 1950s and popularized the jeans-and-T-shirt look well before James Dean did. But, the theatrically-trained actor began shunning his teenybopper image by accepting serious roles like that of Mark Antony in “Julius Caesar” (1953).

He won the Best Actor Oscar for “On the Waterfront” (1954) and took on a wide range of roles after that, garnering popular and critical acclaim as one of the greatest cinema actors of the late 20th century.

Eva Marie Saint (search), who also won an Oscar for her performance in that classic, said Brando was "one of our finest actors."

Born Marlon Brando Jr. in Omaha, Neb., on April 3, 1924, he grew up in Illinois. After he was expelled from the military academy he attended, Brando dug ditches until his father offered to pay for his education.

Brando moved to New York and studied with famed acting coach Stella Adler at Lee Strasberg’s Actors’ Studio, where he adopted the "method approach," which emphasizes characters' motivations for actions and has performers closely identify with the character they're playing.

He created a naturalism that was sometimes derided for its mumbling, grungy attitudes. But audiences were electrified, and a new generation of actors adopted his style.

He made his Broadway debut in John Van Druten's sentimental “I Remember Mama” (1944). Two years later, New York theater critics voted him Broadway's Most Promising Actor for his performance in “Truckline Café” (1946). And in 1947, Brando played his greatest stage role, Stanley Kowalski — the brute who rapes his sister-in-law, the fragile Blanche du Bois — in Tennessee Williams' “A Streetcar Named Desire.”

The Tennessee Williams play thrust Brando into the spotlight, and his first signs of discomfort emerged. The press made much of his weird behavior — his motorcycle, leather jackets and T-shirts and his bongo drum playing. He hated the clamor of fans and suffered through interviews.

The image of Stanley Kowalski seemed to have fallen on Brando, and he once protested to an interviewer: "Kowalski was always right, and never afraid. He never wondered, he never doubted. His ego was very secure. And he had the kind of brutal aggressiveness that I hate. I'm afraid of it. I detest the character."

When Hollywood called, Brando answered, making his film debut in “The Men” (1950) and a year later playing Stanley Kowalski once again, this time in the 1951 film version of “A Streetcar Named Desire.”

Other Brando movies include “Viva Zapata!” (1952), “The Wild One” (1954), “Désirée” (1954) and “Guys and Dolls” (1955). In fact, he was voted by movie exhibitors to be one of the top 10 box-office draws in the country from 1955 to 1958.

His impact on screen acting was demonstrated by Academy nominations as best actor in four successive years: as Kowalski in "A Streetcar Named Desire"; as the Mexican revolutionary in "Viva Zapata!"; as Marc Anthony in "Julius Caesar"; and as Terry Malloy in "On the Waterfront." The latter brought his first Oscar.

Although he remained in Hollywood, he refused to be part of it.

"Hollywood is ruled by fear and love of money," he told a reporter. "But it can't rule me because I'm not afraid of anything and I don't love money."

His image was a studio's nightmare. Millions of words were written about his weight, his many romances and three marriages, his tireless — and, for some, tiresome — support of the American Indian and other causes, his battles with film producers and directors, his refuge on a Tahitian isle.

In the 1960s, his career took a nosedive — with the lowest point being the disastrous MGM 1962 remake of “Mutiny on the Bounty,” which wasn’t able to earn back even half of its monstrous budget.

It was during the filming of “Mutiny,” in which Brando plays Fletcher Christian (Clark Gable’s role in the 1935 original), that he began engaging in self-indulgent, self-destructive behavior on and off the set and got his reputation for being a difficult actor. At work, he threw on-set tantrums and tried to change the script.

He was blamed for a change in directors and a runaway budget, though he disclaimed responsibility for either.

When he wasn’t filming, Brando was eating excessively, having a string of affairs and keeping away from his fellow cast members.

The "Bounty" experience affected Brando's life in a profound way: He fell in love with Tahiti and its people. Tahitian beauty Tarita, who appeared in the film, became his third wife and mother of two of his children. He bought an island, Tetiaroa, which he intended to make part environmental laboratory and part resort.

Brando's career was reborn in 1972 with his brilliant, memorable depiction of Mafia chieftain Don Corleone in Francis Ford Coppola's “The Godfather,” which turned out to be an overwhelming critical and commercial success.

Brando's most famous act of rebellion was his refusal in 1973 to accept the Best Actor Oscar for "The Godfather." Instead, he sent a woman who called herself Sasheen Littlefeather to read a diatribe about Hollywood's poor treatment of Native Americans.

It was roundly booed.

"I don't think the film is about the Mafia at all," Brando told Newsweek. "I think it is about the corporate mind. In a way, the Mafia is the best example of capitalists we have."

Brando proceeded the following year to the highly controversial yet highly acclaimed “Last Tango in Paris,” which was rated X. One of the actor's greatest performances, it was overshadowed by an uproar over the erotic nature of the Bernardo Bertolucci film.

In his memoir, "Songs My Mother Taught Me," Brando wrote of being emotionally drained by "Last Tango," an improvised film that included several autobiographical speeches.

After that, he received huge salaries for playing small parts in such movies as “Superman” (1978) and “Apocalypse Now” (1979). Nominated for an Academy Award for Best Supporting Actor for “A Dry White Season” in 1989, Brando also appeared in “The Freshman” with Matthew Broderick. In 1995, he costarred in “Don Juan DeMarco” with Johnny Depp.

In early 1996 Brando costarred in the film, “The Island of Dr. Moreau.” Entertainment Weekly reported that the actor was using an earpiece to remember his lines.

Brando's years of self-indulgence became apparent later in his life. He weighed well over 300 pounds in the mid-1990s. His crusades for civil rights, Native Americans and other causes kept him in the public eye throughout his career.

Brando’s personal life was marred by unhappiness. As the son of alcoholic, distant, sexually promiscuous parents, Brando had a troubled childhood.

He was married three times to three ex-actresses and had at least nine children — though some reports have said he had as many as 11 or 12.

He married actress Anna Kashfi in 1957, believing her to be East Indian. She was revealed to be Irish, and they separated a year later.

In 1960 he married a Mexican actress, Movita, who had appeared in the first "Mutiny on the Bounty." They were divorced after he met Tarita. All three wives were pregnant when he married them.

His first son, Christian, was sentenced to 10 years in a California state prison for voluntary manslaughter in the death of his sister Cheyenne's fiance, Dag Drollet. Christian claimed Drollet was physically abusing his pregnant sister and said he accidentally shot Drollet in the face during a struggle.

Brando, in the house at the time, gave mouth-to-mouth resuscitation to Drollet and called 911. Christian served half of his jail sentence.

Brando's daughter Cheyenne, in and out of drug rehabilitation centers and mental institutions, later was declared too depressed to raise her child, custody of whom was given to her mother. Cheyenne hanged herself on Easter Sunday in 1995.

"I tried to be a good father," People magazine reported Brando as saying on the witness stand during his son Christian's trial. "I did the best I could."

The glaring spotlight never changed his ways.

"I am myself," he once declared, "and if I have to hit my head against a brick wall to remain true to myself, I will do it."

The Associated Press contributed to this report.