Theodora Keogh, who died January 5 in North Carolina at 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 eldest of three daughters of Archibald Bulloch Roosevelt, the third son of President Theodore Roosevelt. (In later life Keogh played down the Roosevelt connection, forbidding any mention of it to be made in her books.) Her father served in the U.S. 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.

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

As a young girl Keogh wore boyish clothes. She was briefly a debutante before trying life as a dancer, in Canada and then South America. With Alexander Iolas she staged a satire on the married life of Greeks, but the heavy Salvador Dalí costumes proved restricting. Sometimes they performed in the street. It being wartime, a Roosevelt dancing in South America was not considered in the best national interest, and she returned home in February 1943.

Theodora gave up dancing in 1945 when she married the handsome costumier Tom Keogh, two years her junior. The couple moved to Paris, where he designed for the theatre and ballet and worked as an illustrator for Vogue from 1947 to 1951. Tom Keogh designed costumes for films such as “The Pirate” (1948), with Judy Garland, and “Daddy Long Legs” (1955), with Leslie Caron.

In 1952 Keogh 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 Pené du Bois, art editor of the Paris Review. The Keoghs eventually divorced, but remained friends until Tom’s death in 1980. Keogh gravitated to 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). There was much talk of politics; occasional hints of spies lurking; and everyone observed who arrived and left with whom. Keogh left with Hyun.

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. In the Saturday Review, Patricia Highsmith gave an unknown woman a rare favorable 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 neighboring 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 actor John Gielgud of some of the book’s contents. “Not a book for nursery consumption,” writer Peter Quennell added. “Literary censors would not fail to award it an ‘X’ certificate.” Also in 1952, Keogh published “Street Music,” in which a street musician falls in love with a child criminal.

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) fictionalized the murder in 1947 of Elizabeth Short (the Black Dahlia).

The novels were translated into five languages and reissued as 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.” 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 Keogh lived in Rome and then in New York, where she married Thomas (Tommy) O’Toole, a tugboat captain. The couple lived for a while on the boat and later in an apartment in Chelsea. She kept an ocelot that distressed her by chewing off part of her ear. She usually arranged her hair to conceal the injury.

In the 1970s, Keogh and O’Toole sailed for North Carolina but were later divorced. She became a friend of the wife of Arthur Rauchfuss, owner of a chemical plant in Caldwell County. In 1979, after the Rauchfusses divorced, she married Arthur, who died 10 years later.

Keogh spent her final years in a house in the woods, where she kept numerous cats and dog. She gave up keeping chickens as they were eaten by coyotes.