US illustrator Norman Bridwell, creator of the Clifford the Big Red Dog books, has died at the age of 86 following a fall at his home in Massachusetts.

His loveable character first made an appearance in 1963 and went on to star in more than 40 stories, selling 120 million copies worldwide.

Clifford's image has gone on to appear on merchandise and in US buildings, including the White House.

Bridwell had completed two more books which are due for release next year.

Dick Robinson, president of the author's long-time publisher Scholastic said: "We are deeply saddened by the loss of our loyal and talented friend whose drawings and stories have inspired all of us and generations of children and their parents."

His wife of 56 years, Norma, said: "A lot of people were Clifford fans and that makes them Norman fans too."

She was responsible for naming the character Clifford after her imaginary childhood friend.

Over the decades, the bright red dog featured in a host of stories, including Clifford Goes To Hollywood and Clifford and The Grouchy Neighbours, which became popular bedtime reading for children across the US and beyond.

The dog regularly got into trouble before redeeming himself with a daring rescue or doing a good deed.

Bridwell's wife said there were parallels between the author and his creation.

"He's never been able to recognise that. Clifford tries to do the right thing, Norman tries to do right the thing, and he makes a mess of it. But he's the most lovable grown-up man. He's just a nice guy."

Before he found fame with Clifford, Bridwell worked as a commercial artist during the 1950s.

He made numerous attempts to break into children's publishing, until a New York book editor suggested he created a story around an illustration he had submitted of a child and her oversized dog.

Further rejections followed, until publishers Scholastic saw his creation's potential - a move which led to lasting success for the company.

"I said to my wife, 'Now don't count on there being any more. This one is just a fluke. I don't know if there will ever be another one,'" Bridwell said.

In more recent years, the character was animated in a series of cartoons for US television, while a feature film - Clifford's Big Red Movie - was made in 2004.

Bridwell is survived by his wife, a son and three grandchildren. A small private funeral service will be held along with a more public celebration of the author's life and work, his family said.

R.I.P. to another author of classic children's literature... :\'(

I used to enjoy reading the story of Clifford. RIP Norman Bridwell.  :(