Ursula K Le Guin, A Wizard of Earthsea (1968)Read about the other entries on the list at BBC.com Culture.
A young boy known as Sparrowhawk saves his village with a smattering of magic he learned from his aunt, a local witch. Apprenticed to the mage Ogion the Silent, and renamed Ged, he begins his training as a sorcerer. Le Guin’s exploration of the consequences of Ged’s misfires and temptations while at a school for wizards, his struggles with dragons and his inner demons, reshaped fantasy storytelling’s concepts of good and evil. Gradually, Ged gains wisdom as he faces his challenges. "He knew now, and the knowledge was hard, that his task had never been to undo what he had done, but to finish what he had begun." "To me Le Guin’s story is about learning your craft as a writer, the long and painful struggle for mastery of both your art and yourself, written in astounding prose," says Amanda Craig, author and reviewer for the New Statesman and the Daily Telegraph.
A Wizard of Earthsea is among five books that changed Gary Corby and Lev Grossman's top five fantasy novels.