A cause of death was not released.
Hooks joined "SNL" in 1986 and was a part of a cast that included Dana Carvey, Nora Dunn, Phil Hartman, Victoria Jackson, Jon Lovitz, Dennis Miller, Kevin Nealon and A. Whitney Brown. She stayed through 1991.
Often paired onscreen with Hartman, she was known for her impressions of Hillary Rodham Clinton, Nancy Reagan and Tammy Faye Bakker and for playing lounge singer Candy Sweeney of the Sweeney sisters.
"Jan Hooks was an enormous part of my life," actor Kevin Nealon told The Times in an email. "We shared some amazing times; our years as friends, then dating and then the incredible rush of being on 'Saturday Night Live' together."
"I only wish she knew how well respected and admired she was," he said. "This is such a loss."
Born April 23, 1957, in Decatur, Ga., Hooks studied for a time at the University of West Florida in Pensacola before leaving to begin her acting career.
"I was an Indian princess in an outdoor drama in Livingston, Texas," she told the Associated Press in 1991. "I got $115 a week. I couldn't believe it."
After that summer, she worked in dinner theaters and comedy shows -- on stage and, later, on television -- before getting her big break with a role in "Pee-wee's Big Adventure" (1985).
"SNL" soon came calling.
Unlike several other female veterans of the show, she thrived in the male-dominated environment.
“If you're talented, if you're good, you'll get work,” she told the Philadelphia Inquirer in 1994. “It's a waste of energy to complain you're not getting this or that because you're a woman. On 'SNL,' I found that the more you complained, the more you pigeon-holed yourself.”
Celebrities were among those who took to Twitter to express their reactions to her passing.
"RIP Jan Hooks. Loved your work on @nbcsnl especially when you did #sineadoconnor. Condolences to friends/family/loved ones," said actor Orlando Jones.
Hooks' name was trending online worldwide after news of her death broke.