Mr. Bridwell, shown here in 2011, died Dec. 12 at 86. (Charles Sykes/AP)

Norman Bridwell, the children’s author and illustrator who created Clifford the Big Red Dog, the clumsy, lovable canine who has helped teach millions of youngsters how to read, and how to face the world, died Dec. 12 at a hospital near his home on Martha’s Vineyard, Mass. He was 86.

The cause was a recurrence of prostate cancer, said his wife, Norma Bridwell.

Mr. Bridwell’s classic character, a bloodhound the size of a house and the color of a fire engine, joined the literary animal kingdom in 1963 with the publication of “Clifford the Big Red Dog.” With text and illustrations by Mr. Bridwell, it was his first storybook.

At the time, he was struggling to support his family as a commercial artist in New York, and he dismissed the book’s success as a fluke. But children, their parents, teachers and librarians had found something endearing about the story — perhaps Clifford’s loyalty to his owner, Emily Elizabeth, or her faithfulness to him.

Mr. Bridwell’s publisher, Scholastic, went on to commission dozens of Clifford picture books, board books and pop-up volumes. In all, they were estimated to have sold more than 120 million copies. The franchise grew to include games, stuffed animals and an animated show on public television with the actor John Ritter voicing Clifford.

By Clifford’s 50th birthday — a heralded event in children’s literature — he had become an animal celebrity on the order of the monkey Curious George or Babar the elephant.

“He’s a loving dog,” Mr. Bridwell once told the School Library Journal. “He tries to do the right thing. He has good intentions, but his size makes him clumsy, so he causes damage. And then he’s forgiven. All children would like that — to be forgiven for the mistakes they make.”

The Clifford series included “Clifford Gets a Job,” “Clifford’s Halloween,” “Clifford’s Good Deeds,” “Clifford’s Family,” “Clifford’s Bedtime,” “Clifford’s Bathtime,” “Clifford’s Noisy Day” and “Clifford, We Love You.”

Many readers over the years wondered why Clifford was red. The answer, Mr. Bridwell explained, was simply that a jar of red paint was on his desk when he sat down to make his first drawing.

“I dunked my brush in it,” he told the magazine Highlights for Children, “and decided that it would be red.”

He initially planned to name the hulking dog Tiny.

“My wife said that was a stupid idea,” Mr. Bridwell remarked. “And she was right.” Tiny became Clifford, the name of his wife’s girlhood imaginary friend. Emily Elizabeth was named after the Bridwells’ daughter. Their son appeared in “The Witch Next Door,” one of several books that Mr. Bridwell wrote about witches and monsters.

In his text and illustrations, he favored simplicity. He did not set out to impart heavy lessons or wow his readers with virtuosic artwork. Rather, he sought to tell children a story.

“A lot of people who write children’s books sort of write down to a level,” he once told the Boston Herald. “One thing I’ve learned is kids hate that. They hate that baby kind of stuff. They get a lot more of the jokes than people give them credit for.”

Norman Ray Bridwell, the son of a factory worker and a homemaker, was born Feb. 15, 1928, in Kokomo, Ind. He recalled being clumsy, like Clifford, as a boy. His nicknames, he said, included Muscles, “because I had none.”

Mr. Bridwell studied at the John Herron Art Institute in Indianapolis before moving to New York, where he enrolled in the Cooper Union School of Art. He worked for a company that designed necktie fabrics and later drew corporate and promotional cartoons.

In an effort to find more work, he offered his services as a children’s illustrator.

“I made some samples and took them to eight or 10 publishers,” Mr. Bridwell told the Boston Globe, “and was rejected by every one. One young editor said, ‘You’re not very good. No one’s going to buy your artwork. Why don’t you try a story, and if someone buys it, then you could do the art.’ She pointed to a sample painting, of a little girl and a big red dog, and said, ‘Maybe this could be a story.’ ”

Survivors include his wife of 56 years, Norma Howard Bridwell of Edgartown, Mass.; his children, Emily Bridwell Merz of Carlisle, Mass., and Timothy Bridwell of Paris; and three grandchildren.

Once, asked which of the Clifford books was his favorite, Mr. Bridwell named “Clifford and the Grouchy Neighbors.”

“A lot of children have neighbors who complain, ‘Don’t come into . . . my yard! Don’t step on my lawn!’ ” he said. “I thought that could happen to Clifford. The characters look like my mother’s neighbors back in Indiana, but the fact is, they were very nice, considerate neighbors. I hope they never noticed that the grouchy neighbors look like them.”