Joe Ruby, the co-creator of the cartoon series Scooby-Doo, passed away Wednesday.

The BBC reports that Ruby, who created the beloved characters alongside his creative partner Ken Spears, died of natural causes in California.

"He never stopped writing and creating, even as he aged," said his grandson Benjamin Ruby.

Warner Bros' animation president, Sam Register, said Ruby "made Saturday mornings special for so many children, including myself."

Ruby was 87 years old.