Eric Hill, best known as the author and illustrator of Spot, passed away on June 6 at the age of 86 after a short illness at his home in California. His children’s books about a mischievous puppy named Spot have sold over 60 million copies worldwide since the series debuted in 1980.

In a statement, Don Weisberg, the president of Penguin Young Readers Group, said that Hill was “a visionary children’s book author and illustrator who created one of today’s most iconic children’s book characters and changed the landscape of children’s book design with his now ubiquitous lift-the-flap design. Spot has entertained and educated generations of pre-schoolers, a fact that gave Eric much joy. He was very fond of Spot, and we are forever grateful for his contribution to children’s books.”

Hill was a modest man, according to his publisher, who valued simplicity, good design and kindness above all. He was uninterested in public appearances and the trappings of fame and often referred to himself simply as Spot’s Dad.

Born in Holloway, north London in 1927, Hill was evacuated, along with thousands of other city children, to the countryside at the beginning of World War II. Apparently, life in the country didn’t suit him, however, so he returned to London and later found a job in an illustration studio as an errand boy. After the war ended, Hill began working for an advertising agency, which led to a successful career as a creative director and illustrator.

While Hill was freelancing as a creative marketing designer in the late ‘70s, he worked on a paper-engineered novelty piece, which featured a flap, hiding part of the design. His son Christopher, then aged three, was fascinated by the lifting flap. Hill was intrigued by the child’s reaction and invented a story about a puppy, using the surprise-flap idea to entertain him further. This led to the creation of Spot.

Familiar as we are today with a children’s book market where flaps, pop-ups and all kinds of novelty and interactivity are taken for granted, the lifting flap was an innovative concept in the late 1970s. In fact, Hill’s idea was so new that it took a long while before a publisher was willing to publish his first book about Spot.

Published in 1980, Where’s Spot? was an instant hit. Although the lift-the-flap concept was so different, the story itself, told with gentle humor in just a few words, is extremely simple and charming.

Where’s Spot? was quickly followed with Spot’s First Walk. The first animated series, The Adventures of Spot, was developed by King Rollo Films in 1983, using a unique cut-paper technique to build up the movement of the characters while keeping the integrity of the original drawings.

Spot books have been translated into more than 60 languages, and the films have been sold in the same territories.

Hill’s daughter Jane has been an invaluable part of the Spot publishing team for nearly 15 years, utilizing her own design background and intimate understanding of all things Spot to assist Hill as production and business demands increased.

Hill is survived by his wife Gillian Hill, their son Christopher, and his daughter Jane, all of whom are involved in looking after Spot.