A Wizard of Earthsea by Ursula Le Guin

The first book of Earthsea is a tale of wizards, dragons and terrifying shadows.

The island of Gont is a land famous for wizards. Of these, some say the greatest - and surely the greatest voyager - is the man called Sparrowhawk. As a reckless, awkward boy, he discovered the great power that was in him - with terrifying consequences. Tempted by pride to try spells beyond his means, Sparrowhawk lets loose an evil shadow-beast in his land. Only he can destroy it, and the quest leads him to the farthest corner of Earthsea.

'One of the literary greats of the 20th century' Margaret Atwood