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Salazar Slytherin (fl. c. 993) was a pure-blood wizard, noted for his cunning and determination. He was regarded as one of the greatest wizards of the age, respectively as a Parselmouth and as a skilled Legilimens. Slytherin was one of the four founders of Hogwarts School of Witchcraft and Wizardry along with Godric Gryffindor, Helga Hufflepuff and Rowena Ravenclaw, as well as the namesake of the Slytherin House. He mistrusted Muggle-born students to the point of proposing that they should not be accepted at Hogwarts. However, when he expressed his opinion to the other Hogwarts founders, they did not agree with him. In response, he left the school, never to return. Slytherin died sometime near the eleventh century, after creating the Chamber of Secrets, concealing a basilisk, ready to have the Chamber reopened to purge the school of those who, in Slytherin's view, were unworthy to study magic.
Said to be one of "the four most brilliant witches and wizards of the time", Salazar Slytherin founded Hogwarts School of Witchcraft and Wizardry in his adulthood, with friends Godric Gryffindor, Helga Hufflepuff and Rowena Ravenclaw, though he later severed ties with Gryffindor. He even appears to have carefully selected members of his own House.
Salazar Slytherin was known to possess great cunning and determination, qualities he prized in students of Slytherin House. At one point, the Sorting Hat refers to him as "power-hungry Slytherin". He seemed to stop at nothing to get what he wanted; this was proven when he constructed the Chamber of Secrets to purge Muggle-borns, despite the fact that the other founders disagreed with his beliefs. This unrepentant ruthlessness mixed with pure-blood supremacist views would later be adopted by numerous descendants of his, the infamous Voldemort not least of all. Slytherin was also quite proud and vain, as he went to the trouble of immortalising his image in the Chamber of Secrets in the form of a titanic statue standing several dozen feet tall, something that the other three founders were never known to have done. An effigy of such proportions would certainly reflect a grandiose image of oneself. Slytherin is said to be one of the greatest wizards of his age, with extensive abilities, particularly in Legilimency. When considering Sorting a student into Slytherin, the Sorting Hat looks for Slytherin's traits in the student, including cunning, determination, ambition, and resourcefulness.