Klaasen was in the cast of the 1959 South African jazz-influenced musical King Kong.
A daughter of a shoemaker father and a domestic worker mother, she was born in Sophiatown.
In her teens she formed a female quartet, the Quad Sisters.
Klaasen, known for her use of tsotsitaal — a mixture of the slang and languages spoken in the townships, had her face permanently scarred in her teens when a rival threw a mixture of thinners and petrol at her.
She said of the attack: «It is funny that people still make jokes about my face. They call me a cow behind my back. How am I supposed to feel when people treat me like that? «
Klaasen said a music promoter once dropped her from a show because «she has the voice, not the face».
«After that, artists wrote me off. I proved them wrong. But it does not erase the painful things they have said about me,» she said.
In 2006, she was presented with the SA Music Awards lifetime achievement award for her contribution to the music industry.
She was made a member of the Order of the Baobab by President Thabo Mbeki, and given the Imbokodo Award for her contribution to music and the arts.
She died yesterday morning, a few days after her daughter, Lorraine, revealed on Facebook that her mother had pancreatic cancer.
Tributes have poured in since the news of her death broke.
«Ms Klaasen contributed to the country not only as a musician but as a social and political activist outspoken about socioeconomic issues,» said the Presidency.
