Ms. Tennant was presented at court in 1956, and a year later she married Sebastian Yorke, the son of the novelist Henry Green. The marriage ended in divorce, as did her marriages to Christopher Booker, a founder of the satirical weekly Private Eye, and the journalist Alexander Cockburn.

In addition to her daughter Rose, she is survived by her husband, Tim Owens; a son, the writer Matthew Yorke; another daughter, Daisy Cockburn; a sister, Catherine Tennant; a brother, Toby; and three grandchildren.

Under the pen name Catherine Aydy, Ms. Tennant published “The Color of Rain,” a dark satire about the British upper classes, in 1963. Her publishers submitted it for the Prix Formentor, awarded yearly in Majorca, Spain. The chairman of the judging panel, the Italian novelist Alberto Moravia, denounced it as a prime specimen of the decadence of the British novel.

Ms. Tennant found her footing in the early 1970s after discovering writers whose anti-realist qualities dovetailed with her own love of myth, magic and dream. In 1980 she told the reference work World Authors:

“It became gradually clear to me, after meeting British science-fiction writers — J. G. Ballard amongst them — that a way to the center for me lay in the fantastic; and despite the very deep loathing of the British literary establishment for any writing that could be so described, I set out to read as many Latin American and Central European writers as possible, finding confirmation in such works as Bulgakov’s ‘The Master and Margarita’ and the writing of Bruno Schulz that there was nothing inherently ‘silly,’ as the English would have it, in showing the world through lenses both fantastic and real: that the English were indeed limited by a creative feebleness and love of irony which left them out of the most interesting writing, all going on in other parts of the world.”

This new orientation was reflected in “The Time of the Crack” and the two novels that followed, “The Last of the Country House Murders” (1974) and “Hotel de Dream” (1976).

In 1975 she founded the influential literary journal Bananas, which published new work by Mr. Ballard, Beryl Bainbridge, Angela Carter and the science-fiction writer Michael Moorcock. She served as editor for three years.

Her many novels also included “Queen of Stones” (1982), a feminist retelling of William Golding’s “Lord of the Flies”; “Faustine” (1991), about a woman in her late 40s who makes a pact with the Devil to return to her 20s; and “The Beautiful Child” (2010), a ghost story revolving around an unfinished manuscript by Henry James.