Actor Ryan O’Neal speaks at the Smithsonian’s National Museum of American History, in Washington in Feb. 2011, during a ceremony where objects from the private collection of Farrah Fawcett’s estate were donated. Jacquelyn Martin/Associated Press, file

Ryan O’Neal, a boyishly handsome and athletic star of 1970s films – notably as a millionaire Harvard law student in “Love Story” and a Depression-era swindler in “Paper Moon” – but whose erratic talent and tempestuous personal life eclipsed his promise, died Friday. He was 82.

His death was announced on Instagram by his son Patrick, who did not give details. He was diagnosed with leukemia in 2001, but it reportedly went into remission. His later health problems, including prostate cancer, became news updates in the tabloids, where he had long been a familiar presence for his playboy lifestyle, flaring temper, and indulgence in drugs and alcohol.

O’Neal’s excesses had long obscured his acting career. He embraced his reputation as a ladies’ man, squiring a succession of models and actresses, but he was perhaps best remembered as the longtime companion of Farrah Fawcett, the pinup and “Charlie’s Angels” star who died of cancer in 2009 at 62.

Their 19-year relationship ended abruptly when she caught him in their bed with a young actress in 1997. But he returned to her a few years later and was a constant presence with Fawcett through her illness. Yet he revealed to Vanity Fair that, whether from grief or instinct, he had just served as a pallbearer for Fawcett when he made a pass at his estranged daughter Tatum, whom he confused for an attractive Swedish woman.

In interviews, he agreed with the assessment that he was among the worst parents in Hollywood. He described himself as a “hopeless father” and a “pothead” in the 2009 Vanity Fair profile. Several of his children struggled with addiction. His daughter Tatum wrote a memoir describing years of physical and emotional abuse as her father’s star waned and drug abuse rose.

He prodded the acting careers of some of his children, Tatum O’Neal wrote, but could be destructively jealous when they succeeded. He admitted it caused great tensions in his family when Tatum won an Academy Award at 10 for her performance in “Paper Moon” (1973). She played a con artist who may be the illegitimate daughter of his character, Moses Pray.

By all accounts, Tatum outshined her father in the role. In Time magazine, critic Jay Cocks wrote that a mustache and rumpled pinstripe suit could not disguise the fact that he “still looks like the surfer king.”

It was exactly that look – wavy golden hair, blue eyes and lithe boxer’s physique – that briefly propelled O’Neal to the front ranks of Hollywood stardom after an aimless youth. He had been a lifeguard, an amateur boxer and a TV stuntman before his burst to fame playing the spoiled young Rodney Harrington on ABC’s nighttime soap opera “Peyton Place.”

The show, based on Grace Metalious’ steamy novel set in a New England village, aired from 1964 to 1969 and brought O’Neal recognition as a promising young star; cast member Mia Farrow also was singled out for future success.

Tatum O’Neal, left, a cast member in “The Runaways,” and her father, actor Ryan O’Neal, pose together at the premiere of the film in Los Angeles in March 2010. Chris Pizzello/Associated Press, file

Soon after the series ended, O’Neal won his most enduring role, as Oliver Barrett IV in “Love Story” (1970). The film was based on Erich Segal’s novel about a Harvard law student who gives up his fortune to marry a working-class Italian girl (Ali MacGraw), only to see her die of a blood disease.

O’Neal – with the thankless task of reading such lines as “love means never having to say you’re sorry” – was nominated for an Oscar but lost to George C. Scott in “Patton.”

Despite reviews noting its relentlessly goopy premise, “Love Story” was a commercial hit. O’Neal, who never took an acting lesson, was blithe about his performance.

“I didn’t worry a lot about whether I was preparing enough for the part,” he told the New York Times after making “Love Story.” “I’m not into study and research much. I just thought about it as a story about a man and a woman, and I made sure I looked right. You know, the right scarf, the right sweater.”

O’Neal followed with comic capers directed by Peter Bogdanovich: “What’s Up, Doc?” (1972) co-starring Barbra Streisand, followed by “Paper Moon” and “Nickelodeon” (1976) with Burt Reynolds. None duplicated the popularity of “Love Story.”

Especially damaging to O’Neal’s career was “Barry Lyndon” (1975), a costume drama directed by Stanley Kubrick and based on a William Makepeace Thackeray novel. Beautifully photographed, it nonetheless tested viewers’ patience by running more than three hours and was a massive flop. The idiosyncratic casting didn’t help. O’Neal as an 18th-century Irish fortune-seeker seemed stolid at best.

His subsequent work was dim, including the boxing comedy “The Main Event” (1979) with Streisand and the “Love Story” sequel “Oliver’s Story” (1978) with Candice Bergen as his romantic interest. O’Neal was admittedly miscast as Brig. Gen. James Gavin in the all-star World War II drama “A Bridge Too Far” (1977), a film he disparaged publicly.

“It was hard to cast Ryan – he was too beautiful – and I think a lot of men were jealous of him,” talent agent Sue Mengers told Vanity Fair in 2009. “Ryan was very cocky, self-confident, very masculine and gorgeous, and he had every beautiful girl in the world going out with him. It didn’t make him popular with his male contemporaries; he never became pals with the guys who were in the center of things then.”

Charles Patrick Ryan O’Neal was born in Los Angeles on April 20, 1941. His father, also named Charles, wrote for film and television, and his mother, Patricia, was an occasional actress. The family moved around, to Mexico, the British West Indies, England and Germany.

From his travels, Ryan O’Neal said he developed a sense of entitlement and a reputation for brashness. “I knew life was a kick, a fun time,” he told the Times in 1971. “And part of the fun, I guess, was getting into a lot of fights.”

He competed in Golden Gloves boxing championships in Los Angeles in 1956 and 1957 and later invested in pugilists. His interest in brawling led to a quasi-friendship with author Norman Mailer, who cast him as the star of his 1987 film noir “Tough Guys Don’t Dance.”

After his decline in the 1970s, O’Neal starred in a smattering of comedies such as “So Fine” (1981), about a man who starts a trend toward backless jeans, and the critically lambasted satire “An Alan Smithee Film: Burn Hollywood Burn” (1997). Through recent years, he had a recurring role on TV shows, including the Fox series “Bones,” and films such as “Slumber Party Slaughter” (2012).

Despite his fading star, O’Neal did not want for attractive company. There were marriages and divorces from actresses Joanna Moore and Leigh Taylor-Young. He was romantically linked to Streisand, Diana Ross, Ursula Andress and Bianca Jagger. He commenced an affair with Fawcett when she was married to his racquetball partner, actor Lee Majors of “The Six Million Dollar Man.”

Information on survivors was not immediately available. O’Neal had two children from his first marriage, Tatum and Griffin O’Neal; a son from his second, sports broadcaster Patrick O’Neal; a son from his relationship with Fawcett, Redmond, who in 2018 was charged with attempted murder after a series of random attacks but was reportedly found incompetent to stand trial as he underwent mental evaluation; and a brother.

Ryan O’Neal served briefly in jail in 1960 when he assaulted a stranger at a New Year’s Eve party. His wild behavior continued to draw attention. In 2007, O’NEal fired a gun during an argument with his son Griffin. In 2009, he pleaded guilty to drug possession after police found methamphetamine at his home in Malibu, Calif.

“Look, I don’t give myself a break,” he told the columnist Cindy Adams in 2012 while promoting a book about his life with Fawcett. “I had four children. Only sportscaster Patrick’s okay. Griffin’s in prison. Redmond, who feels terrible guilt, is in rehab. Tatum, rehab. I had my own problems. Is all this my fault? I guess, yes.”