US actress Valerie Harper, who scored laughs and stole hearts as Rhoda Morgenstern on back-to-back hit sitcoms in the 1970s, has died at the age of 80.

Longtime family friend Dan Watt confirmed Harper died Friday, eight days after her 80th birthday, adding the family wasn't immediately releasing any further details.

Harper was a breakout star playing the loveable sidekick on The Mary Tyler Moore Show, then as the funny leading lady of the spin-off series, Rhoda.

Later in her career, she played memorable guest roles in TV series like Melrose Place and Sex and The City, in which she played the mother of one of Carrie Bradshaw's boyfriends who shared a special connection with the character. In 2011, she returned to the small screen to play Teri Hatcher's character's aunt in Sex and the City, and two years after that appeared as a contestant on US Dancing With the Stars.

But in recent years, Harper's career took a back seat as she dealt with increasingly serious meidcal problems. In March 2013, she revealed that she had been diagnosed with terminal brain cancer. She had battled lung cancer in 2009, and her husband-manager had said recently that he'd been advised to place her in hospice.

"People are saying, 'She's on her way to death and quickly'. Now it's five years instead of three months ... I'm going to fight this. I'm going to see a way," Harper said of her cancer diagnosis in September 17.

By July 2019, Harper was on a regimen of "a multitude of medications and chemotherapy drugs" and was experiencing "extreme physical and painful challenges" that required "around the clock, 24/7 care.

Tributes are flowing today for Harper from her peers in the entertainment industry:

Harper's death comes two-and-a-half years after the passing of the former co-star she remained closely associated with, Mary Tyler Moore. Moore died in January 2017 from cardiopulmonary arrest complicated by pneumonia, also aged 80.

More to come …