Albus Dumbledore
Albus Percival Wulfric Brian Dumbledore, current Headmaster of Hogwarts school of Witchcraft and Wizardry, Supreme Mugwump of the International Confederation of Wizards and Chief Warlock of the Wizengamot. Albus Dumbledore is undoubtedly one of the most enigmatic figures present in the Harry Potter books. Supposedly the only man Voldemort ever feared, Dumbledore was Professor of Transfiguration when Tom Riddle was at school, and still calls Lord Voldemort 'Tom'. The full extent of Dumbledore's power is unknown, but he may well be the most powerful magic user alive. Certainly he is a figure of great mystery. Dumbledore is possibly the greatest wizard alive, even though by his own admission Voldemort posesses powers Dumbledore will never have, if only because he refrains from using the Dark Arts. He is extremely wise and full of knowledge concerning all manner of magics. Dumbledore is the head of the Order of the Phoenix and its secret keeper, meaning nobody can learn the location of the Order's headquarters without getting it straight from Dumbledore. When Harry's mother saved his life by sacrificing her own, Dumbledore fixed the magic so it would protect him indefinitely, so long as he was under the protection of a blood relative of his mother, such as his aunt Petunia. All the years growing up at number 4 Privet Drive, Harry was magically shielded from the hostilities of Voldemort's supporters, and the Dark Lord himself. So long as he returns there at least once a year, the magic will hold. Dumbledore seems quite fond of sweets, as the password to his office is generally some kind of sweet like fizzing whizzbee or sherbert lemon. He tends not to eat Bertie Botts' every flavour beans though, since he ate a vomit flavoured one he's been rather wary of them, a view reinforced by the one bean he ventured to eat in the mistaken belief it was toffee, when in fact it was earwax.
Professor Sprout
Professor Sprout is a small, earthy witch, with a patched hat and greying hair. She is also the Head of Hufflepuff house and Professor of Herbology. In Harry Potter and the Philosopher's Stone, the second barrier preventing access to the stone is Sprout's Devil's Snare, a nasty plant which squeezes its victims harder the more they struggle to be free. In Harry Potter and the Chamber of Secrets, she teaches Gryffindor and Hufflepuff students to repot mandrakes, magical roots which scream when pulled, a sound which can kill if the mandrake is full grown. Fortunately these mandrakes are only small and the class are equipped with fluffy earmuffs to protect them from the mandrakes' cries. One of the properties of mandrake root is the curing of petrification, so the plants are very useful for restoring all the victims of the Basilisk's stare.