Currie confirmed Socks' death Friday evening and said she was "heartbroken." She did not give details, referring calls to the Clinton Foundation office.
The foundation released a statement from the Clintons:
"Socks brought much happiness to Chelsea and us over the years, and enjoyment to kids and cat lovers everywhere. We're grateful for those memories, and we especially want to thank our good friend, Betty Currie, for taking such loving care of Socks for so many years."
Socks had reached his late teens -- an advanced age for a cat -- when reports surfaced in late 2008 that he had cancer and Currie had ruled out invasive efforts to prolong his life.
"It's not a happy prognosis," presidential historian Barry Landau, a friend of Currie's, said
at the time.
Socks was what feline-lovers call a tuxedo cat -- mostly black with white down the front and belly and on his feet, suggesting a fashionable dandy in a black satin evening jacket with a snowy shirt peeping out. He had markings that looked a bit like a mustache and goatee.
Chelsea Clinton's pet first appeared in the news in November 1992 after then-Gov. Bill Clinton won the presidency and the family was the still in the governor's mansion in Little Rock, Ark. Socks became an early symbol of privacy-vs.-media in the Clinton era when photographers got a little aggressive as he took a stroll outside.
Life changed for Socks in the White House, when his easy access to the out-of-doors was necessarily curtailed. One official conceded that, yes, Socks was on a leash while outside.
Things took a turn for the worse in late 1997, when then-puppy Buddy, a chocolate retriever, arrived. Relations between Socks and Buddy were cool from the beginning.
"I'm trying to work that out," Clinton joked at the time. "It's going to take a while. It's kind of like peace in Ireland or the Middle East."
A few weeks later, in early 1998, the two pets had an encounter on the South Lawn. "A very agitated Buddy approached the cat and began barking as the president restrained him with a green leash," The Associated Press reported. "Socks, hair raised high, stood his ground until Clinton and Buddy made their exit to the Oval Office."
But their pairing enchanted pet lovers, especially children. In 1998, then-first lady Hillary Rodham Clinton put out a book of children's letters to the two pets in "Dear Socks, Dear Buddy."
"Can you please send me a picture and a paw print," one youngster wrote Socks. "Do you have fleas? I think my cat has fleas."
In the book, the first lady wrote she had been taking daughter Chelsea to a piano lesson in spring 1991 when they spotted two kittens in the music teacher's front yard. "The black one with white paws -- Socks -- jumped right into (Chelsea's) arms," she wrote.
After the Clintons left in early 2001, Socks moved in with Currie. Buddy, meanwhile, made the move with the Clintons to Chappaqua, N.Y., but he was struck and killed by a car the following year.
Socks continued to live quietly with Currie, sometimes making appearances at programs held by pet welfare groups. Landau said Socks enjoyed sitting in the sun and that Currie doted on him, cooking him special chicken dinners.