Debbie Reynolds, who starred opposite Gene Kelly in the 1952 musical Singin' in the Rain, has died a day after the death of her daughter, Carrie Fisher.
The US actress, 84, had been rushed to hospital with a suspected stroke.
Her son, Todd Fisher, said the stress of his sister's death had been too much for her and in her last words, she had said she wanted to be with Carrie.
As tributes flowed, Star Trek actor William Shatner said she had been one of the last of the Hollywood royalty.
Reynolds had been at her son's house in Beverly Hills - apparently discussing the arrangements for Carrie Fisher's funeral - when she was taken ill.
She was admitted to Cedars-Sinai Medical Centre suffering from breathing difficulties and her death was confirmed a few hours later. It is thought she suffered a stroke.
Carrie Fisher, renowned for her role as Princess Leia in the Star Wars series, had died aged 60 the day before, after spending three days in a Los Angeles hospital.
She never regained consciousness after suffering a massive heart attack on board a flight from London to Los Angeles on Christmas Eve.
Speaking to the Associated Press news agency about his mother, Todd said: "She's now with Carrie and we're all heartbroken.''
Celebrity news site TMZ reports that Reynolds cracked while discussing plans for Carrie's funeral with her son, telling him: "I miss her so much; I want to be with Carrie."
In other tributes:
- US actress Bette Midler said: "This is too hard to comprehend. Beautiful, talented, devoted to her craft, she follows Carrie, dead days ago"
- US actress Alyssa Milano tweeted: "Dear Debbie Reynolds, I totally get it. Hug her so tight for all of us"
- British actress Joan Collins recalled a "wonderfully warm friend and colleague"
- British comedian Stephen Fry, who earlier tweeted that it had been a "crushing blow to lose Carrie Fisher", offered his "deepest sympathy" to the family at "this new blow"
As people gathered to pay their respects to the actress at Hollywood's Walk Of Fame, one couple, Jose and Daniela Barrera, appeared to speak for many after a year marked by celebrity deaths:
"It's just, you know, a sad time I guess," Jose told Reuters news agency. "With the closing of the year and so many deaths in the year, it's just sad."
"It was so sad," added Daniela. "It was a shocker. I mean, what were the odds of this happening? It was incredible finding out, sad."