Rubeus Hagrid is the man who changes everything for Harry – the person who tells him he is, indeed, a wizard. From this moment on, Harry and Hagrid become close friends – for although Hagrid is a big man, he also has a huge heart to match. At Hogwarts, Hagrid is the Hogwarts 'Keeper of the Keys' and gamekeeper, living in a wooden hut on the Hogwarts grounds. But as kind and lovely as Hagrid is, he does tend to have an interest in scary and terrifying magical creatures – such as a baby dragon and a three-headed dog, to name a few...
Although Hagrid was expelled from Hogwarts, he was allowed to stay on as gamekeeper.