Slytherin is one of the four Houses at Hogwarts School of Witchcraft and Wizardry from the Harry Potter series and the main student antagonists of the franchise, and is traditionally home to students who exhibit such traits as cunning, resourcefulness, and ambition. Given that many of the franchise's villains came from Slytherin, they are the technical main antagonists of the series. Its emblematic animal is the snake and its colors are green and silver. The house ghost is the Bloody Baron. Founded by Salazar Slytherin, the house is composed mostly of pure-blood students, due to its founder's mistrust of Muggle-born witches and wizards. It was headed during Harry Potter's years at Hogwarts by Severus Snape, who was also the Potions teacher. Slytherin house has a negative reputation, with many claiming that it is the source of most dark wizards in Britain, notably Tom Marvolo Riddle, who later became Lord Voldemort, as well as a large majority of his Death Eaters. It has a traditional rivalry with Gryffindor, the protagonistic house that values bravery.
Slytherin corresponds roughly with the element of water.
Notable Slytherin students include Tom Riddle, Dolores Umbridge, Bellatrix Lestrange, Draco Malfoy, his father Lucius Malfoy, Horace Slughorn and Severus Snape, who would be the head of Slytherin house during the events of the Harry Potter franchise.
Not all Slytherin witches and wizards are evil as Horace Slughorn and Andromeda Tonks were good-natured.