By J.K. Rowling
All seven Harry Potter books in one box, the whole way from the cupboard under the stairs to the last battle, enough to swallow a year of a child's reading.
Harry Potter is an orphan sleeping in a cupboard under the stairs until, on his eleventh birthday, a giant named Hagrid tells him he is a wizard with a place at Hogwarts. That is book one. This box holds all seven, and they grow up as your child reads them. The early ones are magic and mischief and Quidditch, a castle full of moving staircases and secrets. By the later books the fun has teeth: a dark wizard returns to power, the school stops being safe, and Harry and his friends Ron and Hermione are fighting a real war. Each book is longer and darker than the one before, following the same three children from eleven years old to seventeen.
This is the series more children have crossed over into long books on than any other, and having all seven in the house is the whole point, because a hooked child finishes one at midnight and reaches straight for the next. The early books read easily for a strong eight- or nine-year-old, and since the story ages alongside the child, the thick, dark final volumes tend to arrive right when they are ready for them. Under the wands it is about a boy nobody wanted turning out to matter enormously, and the friendship between the three holds the whole way through. Once a child falls for book one, years of reading are already sitting on the shelf.