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.
