Diane Keaton’s famous friends took to social media to mourn her death at the age of 79.

The iconic actress died in California, a family spokesperson told People Saturday. The cause of death is unclear.

Keaton’s “The First Wives Club” co-star Bette Midler said she was “unbearably sad” at the news in an Instagram post.

“The brilliant, beautiful, extraordinary Diane Keaton has died. I cannot tell you how unbearably sad this makes me,” Midler wrote.

“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 continued.

Fellow “First Wives Club” star Goldie Hawn also shared an Instagram tribute to Keaton.

“Diane, we aren’t ready to lose you,” Hawn wrote in part. “You’ve left us with a trail of fairy dust, filled with particles of light and memories beyond imagination. … You never liked praise, so humble, but now you can’t tell me to ‘shut up’ honey. There was, and will be, no one like you.”

“We agreed to grow old together, and one day, maybe live together with all our girlfriends,” she also shared. “Well, we never got to live together, but we did grow older together. Who knows… maybe in the next life. Shine your fairy dust up there, girlfriend. I’m going to miss the hell out of you.”

Keaton’s “Book Club: The Next Chapter” co-stars Candice Bergen and Don Johnson also reacted to news of her death to The Post.

Bergen said Keaton’s death was “a huge loss” for her personally.

“Diane was a true artist — tremendously gifted and uniquely talented in so many disciplines yet also modest and wonderfully eccentric. I will miss her terribly,” Bergen said.

Johnson told the outlet, “Diane Keaton … what a trip! She was one of those unique actresses that once she’d realized a character you just couldn’t imagine anyone else’s interpretation. I loved her .. I’ll miss her.”

Kimberly Williams-Paisley, who played Keaton’s daughter in “Father of the Bride” and the film’s sequel, shared a screenshot of the two from the first movie.

“Diane, working with you will always be one of the highlights of my life.,” she wrote. “You are one of a kind, and it was thrilling to be in your orbit for a time. Thank you for your kindness, your generosity, your talent, and above all, your laughter. 🙏🏻🕊️💔❤️❤️❤️.”

Piers Morgan praised Keaton as one of “Hollywood’s greatest actresses.”

“RIP Diane Keaton, 79. Oscar-winning star of Annie Hall, brilliant in the Godfather and Father of the Bride movies. One of Hollywood’s greatest actresses, and a delightful lady. Sad news,” he wrote on X.

Rosie O’Donnell wrote on Instagram, “oh this breaks my heart – love to her children- what style what grace – she will be missed #ripdianekeaton 😥💔.”

Melissa Gilbert also wrote a lengthy message on Instagram, expressing her sadness and noting that Keaton was her idol.

“It seems unreal to me that someone so vital and vibrant is gone,” she wrote. “I know that she will live on through her extraordinary body of work and, most importantly, through her beloved children…but to imagine a world without her here seems…impossible.”

“I loved everything about her,” she continued. “Her versatility and facility as an actor. Her style for sure. Her independence . Her humor. Her smile. Her whole being.”

Amy Sedaris wrote, “Heartbreaking💔💔 A true original. Artist. Beautiful. Spirit in the sky💫💫💫.”

Cynthia Nixon posted a tribute, too, writing, “When I was a kid, Diane Keaton was my absolute idol. I loved her acting. I loved her vibe. I loved her everything. Starting with when I was 12, I tried to dress like her. I wore my hair long. I sported men’s hats and vests and (even though my eyes were fine) I wore bookish glasses because I thought they made me look more like her. A little more than a decade ago I got to be in a movie called Five Flights Up with her and it was like a dream come true. I was very shy around her, but I think she liked me and that meant everything to me.”

“If you wanna know more about Diane Keaton watch Annie Hall, watch Reds, watch Shoot the Moon. She is extraordinary in them,” she continued. “But also read ‘Then Again’ her stunningly honest autobiography which not only tells her own story but contrasts it fascinatingly with her mother’s life. She was one of a kind. I’m so sad she is gone.”