Thorvall was born in Eskilstuna, 110 kilometres west of Stockholm, in 1925. She trained as an illustrator before publishing her first work of fiction in 1959. 'Boken till dig' ('A book for you') became much-loved by teenage readers.
A further string of books for older and younger readers published in subsequent decades earned her literary prizes as well as plaudits from readers and critics.
Publisher Eva Bonnier at Albert Bonniers Förlag worked closely with Thorvall for many years.
"I remember her as a very strong person who wanted close contact with her publisher. She was very professional; one must remember that she used to be a journalist and was accustomed to meeting deadlines," she told news agency TT.
Bonnier recalls too that Thorvall had an intensive personality and thirsted for recognition.
"I think it really pleased her that she received a lot of recognition in the latter part of her writing career. She became an important author and something of an icon for a generation of women. She always took a strong stance for women and worked to make women more visible," she said.
Thorvall regularly found herself in the firing line of public discourse and was routinely excoriated by dissenting commentators. Her notoriety reached its zenith in 1976 with the publication of Forbidden Fruit ('Det mest förbjudna'), an exploration of a middle-aged woman's insatiable sexual appetite.
"Yes, she dared to do things and say things that were perhaps not always appreciated; she dared to stick her neck out," said Bonnier.
Thorvall spent the final years of her life in an elderly care facility.