Summer Magic was a series by writer Alan McKenzie and artist John Ridgway which ran in 2000 AD progs 571 to 577 (1988). It concerned a boy named Luke Kirby who in the summer of 1962 is sent to stay in the countryside with his Uncle Elias — a man he has never met — while his mother is ill. Luke discovers that Uncle Elias is a magian, a practicioner of the alchemical arts, and when a mysterious beast begins stalking the woods around the village and kills Elias's housekeeper Mrs. Birmingham, Elias declares that the creature intends to kill all that he loves in order to get to him, and that Luke must become his apprentice and learn magic in order to defend himself.
Luke learns alchemy, but on the night that they are to hunt the beast Elias has what seems to be a minor heart attack and tells Luke he must face it alone. Luke confronts the beast in the forest and shoots it with an ordinary lead bullet which he mentally transmutes into silver before impact, mortally wounding the creature. Before dying it transforms back into Uncle Elias, freed from his curse in the only way possible as he had planned all along, and Luke is left to reflect on the terrible price all magicians (including, now, himself) must one day pay in exchange for their power: their own humanity.
Summer Magic was a self-contained story, but spawned a lengthy recurring series, The Journal of Luke Kirby, which ran intermittently until 1995. It notably predates other boy wizard stories such as Harry Potter and the DC Comics character Timothy Hunter.