(1950-) A Finnish cartoonist and illustrator. He's mostly famous for his children's books that are actually pretty interesting for even a bit older people; the books have humor, ocassional historical stuff, and above all, good pictures.
His major works include Koiramäki (Doghill) books, about life of anthropomorphic dogs in 1800's Finland. He also made cool books about Santa Claus, half-educational books about some things - sports (Suuri Urheilukirja), life in the night (Yökirja), newspaper reporter's work (Etusivun Juttu), child-targeted parodies about horror stories (Hui Kauhistus!, Vampyyrivaarin tarinoita) and pirates, and even a version of Kalevala, called Koirien Kalevala (The Canine Kalevala).
The books are also very widely translated. I can, simply, recommend them for all children of all ages.