Horace Slughorn

Professor Slughorn had been a professor at Hogwarts and Head of Slytherin House before retiring unexpectedly. He returned to Hogwarts at Dumbledore's request where he resumed his passion for 'collecting' the most famous and interesting students at his infamous dinner parties and recruiting them into the exclusive Slug Club. However, whilst Slughorn appeared to be social and outgoing he was actually hiding a dark secret about his own involvement in Voldemort's rise to power.