Professor Horace Slughorn, a pure-blood wizard, the Potions Master and Head of Slytherin House at Hogwarts School of Witchcraft and Wizardry. He was Potions Professor for over fifty years and Head of Slytherin before retiring in 1981. He was a friend and colleague of Albus Dumbledore, who convinced him to return to the post in 1996. Dumbledore enlisted the help of Harry Potter to accomplish this, together with the help of Slughorn’s own fond memories of Harry’s mother. After retrieving a memory from Slughorn, it became apparent to both Harry and Dumbledore that a young Tom Riddle had used information he finessed from Slughorn to achieve immortality. During the Battle of Hogwarts, Slughorn sided with the defenders of Hogwarts and engaged his former pupil in a duel.