Αλέξανδρος Ιόλας-Θεοδώρα Ρούσβελτ

Theodora and Alexander Iolas: her dancing during wartime was not considered ?in the best national interest?

Theodora Keogh, who has died aged 88, was the author of nine novels, all of them dark in tone and many of them peopled with sinister figures.

The remarkable early novels treated young girls facing sexual conflict in New York and Paris, and critics could not decide whether Theodora Keogh possessed extraordinary understanding of these matters or was merely aiming to shock.

The composer and diarist Ned Rorem described her as "our best American writer, certainly our best female writer", and judged that the Keoghs "represented all that was good about America to everyone in Paris".

She was born Theodora Roosevelt on June 30 1919 in New York, the elder of three daughters of Archibald Bulloch Roosevelt, the third son of President Theodore Roosevelt. (In later life Theodora was to play down the Roosevelt connection, forbidding any mention of it to be made in her books.)

Her father served in the US Army and received the Silver Star in the Second World War. In civilian life he was chairman of Roosevelt & Cross, a Wall Street investment firm. Her mother was Grace Lockwood, from Boston.

Theodora was brought up on the East River, and in the country at Cold Spring Harbor, near Oyster Bay. Her father instilled into her a love of the outdoors with picnics and camping on the sand islands. She was educated at Chapin School in Manhattan, and was finished at Countess Montgelas's in Munich. (The countess, an admirer of Hitler, was to die during the war when her cigarette set fire to her chalet.)

As a young girl Theodora wore boyish clothes, carried a knife and persuaded schoolfriends to swim nude with her. She was briefly a debutante before trying life as a dancer, in Canada and then South America. She joined a ballet company with Alexander Iolas but hated it, so signed up with a musical revue at the Copacabana at Rio, again with Iolas.

Together they staged a satire on the married life of Greeks, but the heavy Salvador Dalí costumes proved restricting. Sometimes they performed in the street. This being wartime, a Roosevelt dancing in South America was not considered in the best national interest, and she and Iolas returned home in February 1943.

Theodora gave up dancing in 1945 when she married the handsome artist Tom Keogh, two years her junior. He was in New York working for the costumier Madame Karinska, and was judged by his friend the costume designer Willa Kim as "one of the most gifted, natural artists" - though in her view he did not make the sacrifices necessary to fulfil his true potential.

Keogh and his new wife moved to Paris, where he designed for the theatre and ballet and worked as an illustrator for Vogue from 1947 to 1951. Keogh designed costumes for films such as The Pirate (1948), with Judy Garland, and Daddy Long Legs (1955), with Leslie Caron. Every Christmas he decorated the façade of the Galeries Lafayette in Paris.

Succumbing to the allure of Parisian high society, Tom Keogh had an affair with Marie-Laure de Noailles, prompting Theodora to embark on one with her chauffeur. As the Baron de Redé put it: "This made their evening travel arrangements rather complicated."

In 1952 Theodora invited the Korean writer Peter Hyun to a Thanksgiving dinner to meet Willa Kim; but this attempt at matchmaking failed when, at the same party, Willa Kim met (and later married) William Pene du Bois, art editor of the Paris Review. Theodora began a two-year affair with Hyun. The Keoghs finally divorced, but remained friends until Tom's death in 1980. "My estranged but still beloved Tom," she called him.

Theodora gravitated to the Café de Tournon in the rue du Tournon on the Rive Gauche. The café was the meeting place for the Paris Review set, including Pené du Bois and the writers George Plimpton and Peter Matthiessen; Alexander Trocchi and Christopher Logue (founders of the literary journal Merlin); and the Alabama writer Eugene Walter.

The author Richard Wright played pinball while others played chess. There was much talk of politics; occasional hints of spies lurking; and everyone observed who arrived and left with whom. Theodora left with Hyun. Occasionally her Roosevelt world encroached as she was whisked away to lunch with Carmel Snow, editor of Harper's Bazaar, sent by her mother.

Theodora Keogh published her first novel, Meg, in 1950. Partly autobiographical (the heroine came from an Upper East Side family), it tackled dark areas - the heroine was raped, and passed her history exam by threatening to expose her teacher as a lesbian.

John Betjeman described it as a "brutally frightening picture of what may happen to a little girl in New York", and Nigel Nicolson wrote: "A great many people will be outraged by this book, but I place it first on my list because of its remarkable originality, good sense and utter lack of sentimentality."

In the Saturday Review, Patricia Highsmith gave an unknown woman a rare favourable review: "She writes with a skill and command of her material that should set her promptly into the ranks of the finer young writers of today."

The Double Door (1952) was inspired by the Marquis de Cuevas, who ran his own ballet on his wife's Rockefeller money and had two adjoining houses in New York, in one of which they entertained grandly. But an internal door led into the neighbouring house, where unspeakable things took place.

This novel had elements of revenge in that Tom Keogh had an affair with Nathalie Philippart, the ballerina married to Jean Babilée, both of whom were briefly signed by the Cuevas Ballet. In the book the Cuevas figure was able to perform his marital duties only when stirred by the memory of a dark, swarthy Indian boy walking in the Place Vendôme.

"Quite something," noted John Gielgud of some of the book's contents. "Not a book for nursery consumption," added Peter Quennell. "Literary censors would not fail to award it an 'X' certificate." Also in 1952, Theodora Keogh published Street Music, in which a street musician falls in love with a child criminal.

Theodora Keogh wrote six further novels. Among them, The Fascinator (1954) had a young girl being lured to bed by a diseased sculptor; Gemini (1961) tackled incest between twins; and The Other Girl (1962) fictionalised the murder in 1947 of Elizabeth Short (the Black Dahlia).

In England the novels were published by the entrepreneurial Peter Davies and later by Neville Spearman. They were translated into five languages, and in the United States became mass-market paperbacks, their covers deceptively adorned with embracing nudes and tabloid captions: "Her haunting beauty drew men to her - her twisted desires consumed them."

Theodora Keogh never read her reviews and abandoned writing after 1962. But, to her great surprise, in the last five years of her life she was tracked down by a disparate group of new readers from various lands, some bearing offers of republication.

After Paris Theodora Keogh lived in Rome and then in New York. Willa Kim sent her to see the Garbo film Anna Christie, an experience which persuaded her to buy a tugboat which she sailed in the Atlantic; it also led to her finding her second husband, Thomas (Tommy) O'Toole, a tugboat captain. After he left her she lived at the Chelsea Hotel, where she kept a margay (a South American tiger-cat) for company. One night, after she had drunk too much and fallen asleep, it chewed off one of her ears.

In the 1970s Theodora Keogh moved to North Carolina, where she became a friend of the wife of Arthur A Rauchfuss, owner of a chemical plant in Caldwell County. In 1979, after the Rauchfusses divorced, she married Arthur, who died 10 years later.

Theodora Keogh, who died in North Carolina on January 5, spent her final years in a house set in 19 acres. She loved cats, but gave up keeping chickens as they were eaten by coyotes.