Maurice Sendak of Ridgefield, who has been called the most important children’s book artist of the 20th century, died on Tuesday in Danbury. He was 83.

Mr. Sendak has been generally acknowledged to be the leading visionary in children’s literature. For more than 50 years, he wrote and illustrated books that have entertained children and adults alike, but have also challenged established ideas about what children’s literature is and should be.

The Times once said Mr. Sendak’s work “has brought a new dimension to the American children’s book and helped change how people visualize childhood.”

His more than 80 books have sold more than seven million copies worldwide in a dozen languages by the year 2000. They included such classics as In the Night Kitchen, Outside Over There, and Where the Wild Things Are.

His many awards include the 1964 Caldecott Medal for the most notable picture book of the year. In 1970, he became the only 20th Century American to receive the Hans Christian Andersen Award in recognition of his entire body of work. And in 1997, President Clinton awarded him a National Medal of the Arts in recognition of his contribution to the arts in America.

Yet, when it first appeared in 1963, his most famous book, Where the Wild Things Are, was greeted with as much controversy as acclaim. Protective parents, teachers and librarians called the story and artwork too scary for children. Some even thought the book could be psychologically damaging because young Max’s mother deserts him and he’s sent to bed to confront his nightmares alone.

But child psychologists said the book helped express hidden childhood fears.

Born in Brooklyn in 1928 to Eastern European immigrants, Mr. Sendak spent much of his childhood in bed, suffering from a variety of illnesses. He read extensively, drew comic strips, and illustrated his older brother’s stories.

His father, a gifted storyteller, entertained the children with disturbing tales of the old country that often ended unhappily.

“These were the stories he told us before we went to bed,” Mr. Sendak said. “No wonder I’m an insomniac. I didn’t know these stories were considered intensely inappropriate for children until I repeated them in school and was sent home to have my mouth washed out. Up until my generation, there was a soft innocence, a sweetness in books for children which I thought was inappropriate. It had nothing to do with my childhood or other people’s as I saw it.”

Mr. Sendak’s experience growing up as a poor Jew in Brooklyn during the Holocaust profoundly influenced his life and work. The monsters in Where the Wild Things Are were inspired by relatives who’d fled the Nazis and come to live with his family in New York.

“They are my uncles and aunts, who poked us, pinched us, said absurd, patronizing things to us, took up all the room, ate up all the food,” Mr. Sendak said.

In his teens, Mr. Sendak studied at the Art Students League and was only 19 when he illustrated his first book, Atomics for the Millions, in 1947 (he did the book for his physics teacher in exchange for a passing grade and a small fee).

When he moved to Ridgefield in 1972, Mr. Sendak had lived in New York City all his life, and had never needed a car.

“I’m a 44-year-old neurotic who just learned to drive,” Mr. Sendak told a Press reporter. “Maybe you should warn them that I drive a green Plymouth.”

Over his years here, his work has expanded into the worlds of opera and ballet; he’s designed sets and costumes for several successful productions, including an opera of Where the Wild Things Are, which was also made into a movie.

He believed his art has always been deeply connected to the music he enjoys. “Designing for operas is as close as I can get to pretending that I’m a musician,” he said at the time.