Children’s author and illustrator Geoffrey Hayes, best known for the comics-style artwork and expressive animal characters in his many titles for emerging readers, died suddenly on June 2, of apparent natural causes, in Asheville, N.C. He was 69.

Hayes was born December 3, 1947 in Pasadena, Calif. and grew up in San Francisco where, from a young age, he and his younger brother Rory would draw picture books and comics for each other. As they entered their teens, the brothers also poured their energy into crafting numerous 8mm movies together.

After high school, Hayes moved to New York City hoping to launch a career as an illustrator and cartoonist. He studied at Hunter College, the Art Students League, and the School of Visual Arts. In the early 70s, he worked in the art department at an advertising firm and also in the interior design department at an architectural firm, both experiences that he said helped him refine his drawing skills. Simultaneously, Hayes had been building a portfolio of his artwork and in 1974 brought it to Harper & Row, where he met with then-editor Edite Kroll, who published his first picture book, Bear by Himself, in 1976. Kroll continued as his editor at Harper and in 1982 became his literary agent.

Hayes primarily wrote his own stories but also illustrated several works by other authors, including When the Wind Blew (Harper, 1977) by Margaret Wise Brown, which was selected as a New York Times Best Illustrated Book of the Year. Hayes’s popular Otto and Uncle Tooth early reader series for Random House has sold more than 1.5 million copies.

More recently, Hayes was able to indulge two of his passions when he was published at TOON Books, working with founder and editorial director Françoise Mouly. His title Benny and Penny in Just Pretend appeared on TOON’s inaugural list in 2008. “Comics have always been my first love,” Hayes told Colorado Parent magazine in 2010. “I’m really drawn to sequential art.” In that same interview, he went on to describe some of his creative process. “In fact, when working out ideas for regular children’s books I usually start with thumbnail sketches with word bubbles,” he said. “It helps me get a better sense of the personalities and actions. I wrote the first Benny and Penny story as a portfolio piece and decided to do it as a comic for my own amusement. At the time, their names were Tyler and Bella. I showed this to Françoise, and together we decided that it would make a good TOON book.” Hayes’s Benny and Penny in the Big No-No!, (TOON, 2009) won the 2010 Theodor Seuss Geisel Award, which recognizes the most distinguished American book for beginning readers.

In all, Hayes created more than 50 books for children. At the time of his death, he was at work on what he called his “dream project,” a 144-page original fairytale in graphic novel format called Lovo and the Firewolf, which was under contract at Fantagraphics.

Edite Kroll, his agent and former editor, recalled her longtime friend: “I remember my very first meeting with Geoffrey Hayes at Harper in 1974, when I was a junior editor meeting him, an unpublished artist,” she said. “At that time, we all followed Ursula Nordstrom’s edict that each artist who wanted to show his work was to be seen by an editor—after all, it might be the next Silverstein or Sendak!

“After dutifully looking through Geoffrey’s portfolio filled with samples done in many different styles, all accomplished but none very personal or special, I asked what he had in that little envelope not yet opened. Well, he told me, it’s not a book, just little moments. Those little moments were all about a little bear who had to be alone by himself at times ‘to think his own thoughts and sing his own songs...’ I fell in love with Geoffrey’s delicate, evocative watercolor sketches of these little moments and we worked together to turn them into his very first published book, Bear by Himself, in 1976. It was a wonderful 40-plus years of first working as his editor and then his agent—and friend—and to enjoy watching him hone his talent as both artist and writer. It’s very sad that the book he was working on passionately because it was closest to his heart, Lovo and the Firewolf, will not now be finished.”

Random House Children’s Books editorial director Heidi Kilgras recalled her times working with Hayes on the Otto books and other projects. “Working with Geoffrey was a joy,” she said. “He was so sharply attuned to what would interest kids and make them laugh. I will greatly miss his peaceful spirit, and his most puckish characters.”

Françoise Mouly, founder and editorial director of TOON Books, offered this tribute: “It does feel as if we have lost a family member. Geoffrey was part of who we are, because we shared common values: an intense dedication to doing the best we can in our publishing endeavors, not just in spite of the fact we are publishing books for children, but very much because we are publishing books for very young children. Geoffrey’s life had been shaped by the stories his mother told him, the books she read to him and his brother. He understood, as few authors understand, that doing books for kindergarteners is a momentous responsibility. He knew that the youngest children are the harshest critics, the most attentive readers, but he also knew that they offer those who reward their attention the most lasting reward, that of letting themselves be shaped by the book they read, of growing up with each book they read, and letting the author be a part of who they become. And if they are now, as Geoffrey was, thoughtful and kind–he was at heart a very convincing Benny to the charming Penny–and if they have learned how to overcome fear and pet peeves, if they know how to embrace and disarm a bully and gather their courage to explore new territory, then Geoffrey Hayes the author will live forever in that legacy, one small comic book at a time. Long live Geoffrey Hayes; may his books continue to delight children for years to come.”