Professor Salazar Slytherin was a pure-blood wizard of the medieval times. He was a Parselmouth (a wizard with the rare ability to speak to snakes) and skilled at Legilimency. He was one of the four founders of Hogwarts School of Witchcraft and Wizardry and the former best friend of Godric Gryffindor, a fellow founder. Slytherin didn't trust Muggle-born students, and he expressed his opinion by proposing that they should not be accepted at Hogwarts. However, when the other Hogwarts founders didn't agree, Slytherin created the Chamber of Secrets, concealing a basilisk inside. He left the school soon afterwards, never to return and died at some point in the Middle Ages.