Slytherin

"Or perhaps in Slytherin, You'll make your real friends, Those cunning folk use any means, To achieve their ends."

- The Sorting Hat

Slytherin is one of the four Houses at Hogwarts, and is traditionally home to students who exhibit such traits as cunning and ambition. Slytherins are also known for thinking before they act, (unlike Gryffindors) and for being generally sneaky. (i.e. When they break rules, they rarely get caught.) Founded by Salazar Slytherin, the house is comprised mostly of pure-blood students, due to its founder's mistrust of Muggle-born witches and wizards. Most Dark witches and wizards came from this House, most notoriously Lord Voldemort. Slytherin corresponds roughly with the element of water.

Slytherin's head of house for Harry's first six years of school was Severus Snape; however, as he fled with the Death Eaters at the end of Harry Potter and the Half-Blood Prince, Potions teacher Horace Slughorn became the head of Slytherin House. The Slytherin common room may be found in the dungeons of Hogwarts castle, and are located underneath the lake in the school grounds.

The Sorting Hat claims that blood purity is a factor in selecting Slytherins. This suggests that it bases its decisions more upon the views of its members, than directly on any accurate test of blood. There is no reason to believe that muggle-born students are not sorted there, merely that pure-blooded students are more desirable to that house. There are definite examples of half-bloods in the house (Snape, Voldemort), and one notable example of a half-blood who was nearly sorted into the house (Harry Potter). The fact that Rowling intended to place a character named Mafalda, a half-blood who was the daughter of a Squib and a Muggle, in Slytherin, suggests that Rowling at least does not view the Slytherin House desire for blood-purity as particularly influential upon the Sorting Hat. Mafalda was intended to be a cousin of the Weasley children..

According to Albus Dumbledore, the qualities which "Slytherin prized in his hand-picked students" include "Parseltongue...resourcefulness...determination...a certain disregard for the rules": which Dumbledore notes are qualities possessed by Harry Potter.

Contrary to the wishes of the other founders, Salazar Slytherin wanted a stricter policy of admittance&mdash;one limited to pure-blood students. The controversy this created apparently led to Salazar leaving the school and the Chamber of Secrets behind. A millennium later, the house's students are still considered affiliated with Salazar's reputed views although some half-bloods, most notably Voldemort and Snape, have been in Slytherin. "Pureblood" lineage is certainly one of Voldemort's public goals. It is often mentioned in the novels (especially in Philosopher's Stone and Chamber of Secrets) that most of the dark wizards were in Slytherin (though how many were from this house before Tom Marvolo Riddle began recruiting there is unstated: as his own House, it was certainly most easy for him to recruit there).

However, it must be noted that good Slytherin wizards also exist: most notable in the canon is Horace Slughorn, a member of the House prior to the entry of Tom Riddle. Another notable Slytherin member is Andromeda Black, who while related to many different dark wizards (most notably her sister Bellatrix Lestrange, her brother-in-law Lucius Malfoy, and her nephew Draco Malfoy), chooses to forsake the loyalty to her family (the House of Black) in marrying the Muggle-born Ted Tonks. Also, the allegiance of Severus Snape is found to be ultimately towards Albus Dumbledore, serving as a triple agent for the Order of the Phoenix.

Cunning and ambition are easily turned towards ill purposes, but are not inherently negative; furthermore, daring, intelligence, and loyalty can as easily become negative. A reason Slytherins may not be thought of as the best kind of people is because many of them seem to value their own lives more than the lives of others. When Harry is trying to run away, because he is afraid that his presence is putting his friends' lives in danger in Chapter 23 of Harry Potter and the Order of the Phoenix, Phineas Nigellus sees him and says, "We Slytherins are brave, yes, but not stupid. For instance, when given the choice, we will always choose to save our own necks." There are exceptions to this rule however, such as Snape, who Harry said about that he was a "Slytherin and he was probably the bravest man I ever knew". Rowling herself has defended Slytherins, claiming that while most Dark wizards are Slytherins, most Slytherins are not Dark, and smaller groups of Voldemort's supporters are aligned with other Houses. Slytherin, along with Gryffindor, is one of the best and most competitive houses at Quidditch and is often in the lead for the House Cup, having won six times in a row, prior to Harry Potter arriving at Hogwarts.