In a career spanning 50 years, she wrote more than 60 novels, as well as serving as a Labour member of the House of Lords.
Her most famous creation was Inspector Wexford, who appeared in 24 books.
But she also wrote more than two dozen standalone novels, and a further 14 under the pen-name Barbara Vine - an amalgam of her middle name and her great grandmother's maiden name.
Ruth Barbara Grasemann was born in 1930, in South Woodford in Essex, the only child of Ebba Kruse, who had been born in Sweden and brought up in Denmark, and Arthur Grasemann, who was English.
Her childhood was reputedly unhappy, but she rarely spoke of it in interviews, just as she refused to talk about the mystery of her marriage and divorce. She wed Don Rendell, a journalist, in 1953; the couple divorced in 1975 but remarried two years later. They had one son.
Rendell herself started out as a journalist on a local Essex newspaper, but resigned after filing a story about an after-dinner speech in which she failed to report that the speaker dropped dead halfway through - she hadn't been there.
The first Wexford book, From Doon with Death, appeared in 1964.  It was also her first published novel: she was paid an advance of Â£75.
Wexford - played in the successful television adaptations by George Baker - shared many of his creator's convictions and prejudices, though he was a Liberal Democrat and Rendell always described herself as a socialist.  "The way he thinks, and his principles and ideas and what he likes doing, that's me," she told one interviewer.
The books were conventional crime stories, but the settings were contemporary and convincing - and while the novels' structures may have been conventional her way of writing them sometimes was not.
"I have an idea and I have a perpetrator and I write the book along those lines," she said in a BBC interview, "and when I get to the last chapter I change the perpetrator, so that if I can deceive myself I can deceive the reader."
But as well as the Wexford books, she wrote more than two dozen standalone novels, often featuring misfits and deviant characters on the margins of society.
And in 1986, she began publishing darker psychological thrillers as Barbara Vine.  They were, she said, more searching, more serious and more analytical than her other books.  And she admitted more than once to being fascinated by other people's secrets.
Many of her books did not just present readers with a puzzle but linked murder and crime with social injustice or economic disadvantage.
In Rendell's world, the conservative instincts of middle England often helped to provoke antisocial and irrational behaviour rather than keeping it in check.
That reflected her own political views.  Appointed a CBE in 1996, she was elevated to the House of Lords as a Labour peer in 1997.  She spoke out against racism, sexism and class disadvantage, and among her achievements as a working peer was the introduction of a 2003 act which made it a crime to send girls abroad to be subjected to female genital mutilation.
Fifteen years ago, her fellow crime-writer Val McDermid described her as unique among British crime writers.  "No-one can equal her range or her accomplishment; no-one has earned more respect from her fellow practitioners.
"The broad church that is current British crime writing owes much to a writer who has... consistently demonstrated that the genre can continually reinvent itself, moving in new directions, assuming new concerns and exploring new ways of telling stories."
And Ruth Rendell herself said of her 40-year friendship with another queen of the genre, PD James: "Both of us thought more about the characters than the crime."
Ruth Rendell was a leading member of the generation of writers who took crime fiction and turned it into literature.