Norman Bridwell, who created the beloved Clifford the Big Red Dog children’s book series, has died. He was 86.

Bridwell died on Friday at Martha’s Vineyard Hospital, reports The Martha’s Vineyard Times.

The author was born in Kokomo, Indiana in 1928 and studied art in Indianapolis and New York before he began working as a commercial artist. In 1962, he decided to illustrate children’s books, but a Harper & Row editor suggested that he write his own stories to go with his art. At that point, he created Clifford, a giant red dog owned by Emily Elizabeth, a little girl named after his daughter.

Just three weeks after he submitted the idea to Scholastic Books, they offered to publish it and the rest is history.

“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,” Scholastic CEO Dick Robinson said in a statement to the Los Angeles Times. “What comforts the reader is that Clifford is always forgiven by Emily Elizabeth, who loves him unconditionally.”

Over five decades after Clifford was first introduced, the dog has starred in 40 stories, which have sold a combined 129 million copies and were translated into 13 languages. PBS produced an animated series and Universal announced a Clifford movie for 2016.

Bridwell is survived by his wife, their son and daughter and three grandchildren. He is also survived by Clifford, who stars in Clifford Goes To Kindergarten, out in May 2015, and Clifford Celebrates Hanukkah, out in fall 2015.