Russell Hoban, the prolific fantasy and children’s author perhaps best known for “Riddley Walker,” a post-apocalyptic novel that relied on a language he created, has died, his publisher said Thursday. He was 86.

The former illustrator, painter and decorated World War II veteran passed away in London on Tuesday night, Bloomsbury Publishing said. The cause of death was not immediately available.

“Russell Hoban was a complete original,” said Bill Swainson, his editor at Bloomsbury. “People who only read his adult fiction don’t know he was also one of the great children’s writers of our time.”

He said Hoban was productive until nearly the end of his life and had published a novel last year.

Hoban was born in Lansdale, Pennsylvania, but moved to London in 1969. He attended the Philadelphia School of Industrial Art before serving in the U. S. Army as an infantryman in Europe in World War II. He was awarded the Bronze Star in 1945.

Upon his return to the United States after the war, he worked at various jobs before launching a career as a freelance illustrator in 1956 and working as a copywriter. His paintings were occasionally used as cover portraits on major magazines.

Hoban started writing children’s books a few years later, eventually writing more than 50, including “The Mouse and His Child” and his series of books dealing with a badger named Frances.

Hoban turned to adult fiction in the 1970s, writing several novels before producing “Riddley Walker,” the work many regard as his masterpiece, in 1980.

The novel is set 2,000 years in the future after a nuclear war has destroyed much of the world. The book relies on a language Hoban created, based on English, that characterizes the near-death of the human spirit.