Eartha Kitt, the US singer, dancer, actor and self-proclaimed "sex kitten" whose career spanned six decades, has died in the United States aged 81.

One of the entertainment world's most versatile performers – she was nominated for Emmys, Tonys and Grammys – Kitt was perhaps best known for her sultry, cat-like purr, which took in both her speaking and singing voices. A family spokesman said Kitt died yesterday in Connecticut after treatment for colon cancer.

The cancer was first treated two years ago but recurred after a period of remission, Andrew Freedman told Reuters. "She came back strongly. She had been performing until two months ago," he said. "We had dates booked through 2009."

Kitt, who published three autobiographies over the course of her long career, had a difficult childhood as a mixed-race daughter of the American South before starting her entertainment career as a dancer with the famed Katherine Dunham troupe.

Her best known songs included C'est Si Bon, Let's Do It and Just an Old Fashioned Girl, as well as the Christmas staple, Santa Baby. Kitt was ostracised in America for speaking out against the Vietnam war in the 1960s.

Famously called the "most exciting woman in the world" by Orson Welles, Kitt spent much of her life single, though brief romances with the rich and famous peppered her younger years. In 1960, she briefly married Bill McDonald, but separated from him after the birth of their daughter.

After making headlines singing in the Broadway revue, New Faces of 1952, Kitt released her first album in 1954, which included Santa Baby.

Her acting career saw her star opposite Nat King Cole in St Louis Blues in 1958. Her best known television role was as Catwoman in the 1960s Batman series.

Always blunt about her beliefs, Kitt made her feelings about Vietnam known as she attended a White House lunch hosted by Lyndon Johnson's wife in 1968, when her fame was near its peak.

"You send the best of this country off to be shot and maimed," she told the group of about 50 women. "They rebel in the street. They don't want to go to school because they're going to be snatched off from their mothers to be shot in Vietnam." For the next four years, Kitt performed almost exclusively overseas.

She talked widely about her deprived childhood in South Carolina, where she said her mother was black and Cherokee and her father was white. She subsequently lived with an aunt in New York, where she attended stage school.

Kitt was unsure of her birthplace or birth date until in 1997 a group of South Carolina college students located her birth certificate, which gave her birth date as 17 January 1927. Kitt had always celebrated on 26 January.

"I'm an orphan. But the public has adopted me and that has been my only family," she said.