Author and illustrator Norman Bridwell died on Friday, Dec. 12, in Martha’s Vineyard at age 86. His publisher, Scholastic, announced the news Tuesday, but did not give a cause of death.

Bridwell was best known for creating the Clifford the Big Red Dog book series. First published in 1963, Bridwell eventually wrote and illustrated more than 150 Clifford titles. The series has been translated into 13 languages, and sold 129 million copies. Moreover, the lovable canine also found a home in television with PBS Kids’ animated series, which was on air between 2000 and 2003. Plus, David Bowers is directing a big-screen adaptation, which is set for a April 8, 2016 release date.

“Norman Bridwell’s books about Clifford, childhood’s most loveable dog, could only have been written by a gentle man with a great sense of humor,” Dick Robinson, Chairman, President and CEO, Scholastic, the global children’s publishing, education and media company, said in a release. “Norman personified the values that we as parents and educators hope to communicate to our children – kindness, compassion, helpfulness, gratitude – through the Clifford stories which have been loved for more than fifty years.”

Robinson added: “The magic of the character and stories Norman created with Clifford is that children can see themselves in this big dog who tries very hard to be good, but is somewhat clumsy and always bumping into things and making mistakes. What comforts the reader is that Clifford is always forgiven by Emily Elizabeth (named after Bridwell’s daughter), who loves him unconditionally. At Scholastic, 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.”

Bridwell is survived by his wife, Norma, their daughter, Emily Elizabeth, son, Timothy, and three grandchildren. Bridwell finished two more Clifford books prior to his passing, both of which will be released in 2015. Clifford Goes to Kindergarten will hit shelves in May, and Clifford Celebrates Hannukah will come out in October.

For Scholastic’s full statement, click here.

To watch Clifford’s 50th anniversary video, which features an interview with Bridwell, click here.

This article originally appeared on EW.com

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