Thomas M. Disch, who died July 4 at 68, was the author of dozens of books.

A genre-defying powerhouse of a writer, he was best known for such science fiction novels as “The Genocides” (1965), “Camp Concentration” (1968), and “On Wings of Song” (1979), a Hugo Award finalist about a device that enables singers to transcend their bodies. As his reputation grew, he came to be identified with a “new wave” of science fiction writers including Ursula Le Guin and Michael Moorcock.

But Disch, who was reportedly found dead at his apartment of a self-inflicted gunshot wound, ranged widely from horror to gothic romance to poetry. One of his children’s books, “The Brave Little Toaster” (1986), about a group of appliances that go in search of their owner, was turned into an animated film.

Reviewing “About the Size of It” (2007), a collection of Disch’s poems, The New York Sun’s Eric Ormsby had fulsome praise for his wordplay in praise of obesity and even the dot on the letter “i.” “You have the feeling that the marvelous timing, the clever rhymes, the melodious stanzas, are not produced for mere effect but serve to channel a tremendous exuberance,” Mr. Ormsby went on.

A longtime New Yorker, Disch served for several years as a drama critic for the Nation. He was also a drama critic at the New York Daily News during the 1990s. For the Sun, he wrote art criticism during 2003 and 2004, including the newspaper’s occasional Gallery-Going column.

Newsweek critic Walter Clemons once wrote that Disch was “the most formidably gifted unfamous American writer,” and Disch seemed not to resent his relative obscurity. “It would have been very easy for me to perform according to the publishers’ expectations and turn out a succession of books that could be marketed as, ‘Here’s another one just like the last one!'” he told Publishers Weekly in 1991. “It’s easy to market product that way. As it is, I present difficulties to the sales force.”

Born February 2, 1940, in Des Moines, Iowa, Disch spent most of his childhood in the Minneapolis/St. Paul area, where his father was a door-to-door magazine and encyclopedia salesman. Disch seemed at first to follow in his father’s footsteps, hawking pot holders and greeting cards door-to-door as a teenager, but after finishing high school in 1958 he moved to New York. He took classes at New York University and worked selling orange juice at the theater where “The Music Man” was playing. While working at a succession of jobs including advertising copywriter and funeral parlor watchman, Disch began writing science fiction for magazines including Fantastic Stories and Amazing Stories. He quit his jobs to write full-time in 1964. In 1965 he published “The Genocides,” about an invasion of aliens who enslave the human race. Disch’s books began appearing at a rate of one or two each year, many of them under pseudonyms. In addition to narrative fiction, he produced an interactive computer fiction called “Amnesia” (1985), the libretto for an opera version of “The Fall of the House of Usher” (1979), and he was scriptwriter for a 1987 episode of “Miami Vice.”

Asked in the Publishers Weekly interview how he wrote so much, Disch said: “I would ask, on the contrary, how do people who are full-time writers and don’t have jobs teaching write so little?”

Big and bearded, Disch lived with his long-time companion, the poet Charles Naylor, in a book-crammed railroad apartment overlooking Union Square. Among their décor was a discarded, pink-clad Gimbels dummy dubbed Huguette Wadju-Peiffer. Disch and Naylor collaborated on several books, notably “Neighboring Lives” (1981), a historical fiction about Thomas Carlyle and his artistic circles.

Friends said Disch had been despondent over ill health and Naylor’s death in 2005. Yet he seemed in good humor for a brief Publishers Weekly interview last spring about his most recent book, “The Word of God.” An outspoken atheist, Disch adopted the deity’s perspective to score points on the absurdity of hell and similar numinous postulates.

“One of the wonderful things about being God is you can say such nonsense and it’s all true,” he said.

Three brothers and a sister survive him.