The Moomintroll series by Tove Jansson

These books are the absolute best. Stories full of curiosity and the beautiful freedom of childhood and love. They impacted the culture of our family in many, many ways. If you can get the Drawn and Quarterly editions, do it! They are gorgeous and will train your young people to always love a book that needs a map at the beginning to set the scene. My son told people we had made a mistake and that his actual name was Snufkin for YEARS.