Hollywood legend Diane Keaton has died at 79.

The Oscar winner, whose glittering career spanned more than half a century, died Saturday in California, her family confirmed. A cause of death was not disclosed.

Keaton, who rose to fame in the 1970s, starred in hit films including “The Godfather,” “Annie Hall,” “Baby Boom,” “First Wives Club” and “Something’s Gotta Give.”

The actress last posted to her Instagram on April 11, sharing a photo with her dog, Reggie. She had not been seen publicly in six months.

The vivacious icon was equally known for her off-screen presence, beloved for her whimsical sense of humor and her signature style, wearing tuxedos, turtlenecks, bowler hats and black-rimmed eyeglasses.

Keaton, who was also a writer, director, photographer and singer, was additionally famed for her relationships with a string of Hollywood stars, including Al Pacino, Warren Beatty and Woody Allen.

She is survived by her two children, Dexter, 29, and Duke, 25, whom she adopted after her 50th birthday.

An anonymous friend told People that Keaton’s health “declined very suddenly, which was heartbreaking for everyone who loved her.”

“It was so unexpected, especially for someone with such strength and spirit,” they stated. “In her final months, she was surrounded only by her closest family, who chose to keep things very private. Even longtime friends weren’t fully aware of what was happening.”

Born in Los Angeles, Keaton made her film debut in 1970 in “Lovers and Other Strangers.”

In 1972, she became a household name with a star turn as Kay Adams-Corleone in “The Godfather,” starring opposite Marlon Brando and Al Pacino, the latter of whom she had an on-off relationship with for a decade.

That same year, Keaton appeared opposite Woody Allen in “Play It Again, Sam.” The pair briefly dated, before the relationship turned platonic.

However, it was the start of a decades-long collaboration and lifelong friendship. They worked on eight films together, including “Annie Hall,” for which Keaton won both an Oscar and a Golden Globe in 1978.

The legendary director was reportedly devastated by the news that his muse, former girlfriend and longtime defender had died.

“He is extremely distraught and surprised and upset,” a source close to Allen told People. “It makes him think of his own mortality.”

In 1979, Keaton began a relationship with Hollywood heartthrob Warren Beatty, with whom she starred in the 1981 epic, “Reds.” The relationship ended around the time of the film’s premiere.

She continued to charm audiences across the 1980s and 1990s, with roles in critically acclaimed and beloved comedies such as “Baby Boom,” “Father of the Bride” and “First Wives Club.”

In 2003, she won her second Golden Globe for her role opposite Jack Nicholson in Nancy Meyers’ box-office sensation “Something’s Gotta Give.”

Keaton worked consistently over the following two decades, making more than 20 films in 20 years.

Among the most famous: “The Family Stone” (2005), “Because I Said So” (2007) and “Book Club”(2018).

Her last film was the comedy “Summer Camp,” released last year.

A multihyphenate, Keaton also directed the 2000 comedy “Hanging Up,” in which she appeared opposite Meg Ryan, Lisa Kudrow and Walter Matthau in his final screen role before his death. The film’s screenplay was written by “You’ve Got Mail” scribes Delia and Nora Ephron.

Keaton was also a singer, releasing the holiday song “First Christmas,” last year.

She also had a keen interest in architecture, photography and interior design, publishing several coffee table books, including “The House That Pinterest Built” in 2017.

The star further released her own label of wine, and penned two best-selling memoirs, “Then Again,” published in 2011 and “Brother & Sister,” published in 2020.

In 2017, she was honored by the American Film Institute with a Lifetime Achievement Award, where she was honored by stars including Reese Witherspoon, Emma Stone and Meryl Streep.

“She has given us so much happiness,” Streep said onstage at the time, remarking on Keaton’s glittering career.

News of Keaton’s death sent shockwaves through Hollywood, with a stream of stars taking to social media to pay tribute to the icon after the news broke Saturday.

“First Wives Club” co-star Bette Midler was among the first to post, writing: “The brilliant, beautiful, extraordinary Diane Keaton has died. I cannot tell you how unbearably sad this makes me.

“She was hilarious, a complete original, and completely without guile, or any of the competitiveness one would have expected from such a star. What you saw was who she was…oh, la, lala!,” she added.