Slytherin

"Slytherin house values ambition, cunning, resourcefulness, and pure blood heritage.

The founder of the house is Salazar Slytherin.

The Sorting Hat claims that blood purity is a factor in selecting Slytherins .Slytherin House seems to have attracted more evil wizards than any other house, including Voldemort himself and almost all of his supporters. However, Slytherin itself is not evil; it's just that having ambition as a core quality results in a disproportionate amount of self-important, competitive students."