Everyone has taken at least one quiz to find out what Hogwarts house they would fall into if they were lucky enough to receive an owl inviting them to attend Harry Potter's school. The wider world likes to simplify these house traits into their most basic forms. If you’re brave you’re in Gryffindor, if you’re smart you’re in Ravenclaw, if you’re kind you’re in Hufflepuff, and if you’re evil you’re in Slytherin.
Slytherin is perhaps the most misunderstood house (it’s not every Slytherin’s fault that Voldemort hung out in their common room any more than it is every Ravenclaw's that Gilderoy Lockhart hung around in theirs). Not every brilliant wizard wore Ravenclaw blue. Slytherin has had quite a few brilliant students of their own.
Andromeda Tonks
Least known, but certainly not the least important, of the famed Black sisters (also including Bellatrix and Narcissa) Andromeda followed family tradition and fell into House Slytherin upon arrival at Hogwarts. Why was she a Slytherin? Because you have to be both cunning and wise to outsmart your own family.
This independent witch married outside the house (Hufflepuff and muggle-born, Ted Tonks), aided The Order of the Phoenix, and raised Teddy Lupin all on her own. Author of many letters, and a brilliant student who fought the Dark Lord even under torture. Much respect for this stereotype breaker.
Draco Malfoy
Everyone’s favorite Slytherin bad boy was actually no slouch when it came to his school work. Draco made it into multiple N.E.W.T level courses following successful completion of his O.W.L examinations. He was also talented at occlumency. Let us not forget that in the fifth Harry Potter book he was also made a prefect (not an honor usually bestowed upon those with failing marks in any house).
While his friendship with the likes of Crabbe and Goyle did not reflect well on the boy’s intelligence, his softer side and self-expression came through with his relationship with Moaning Myrtle. He took her into his confidence while struggling to fix the vanishing cabinet in his sixth year. He had a lot to say. And, in the end, was successful in his task.
Scorpius Malfoy
Sometimes genius can run in the family. While considerably different from his father, Scorpius Malfoy was a brilliant Slytherin student while at Hogwarts. Raised largely out of the public eye, Scorpius spent much of his pre-Hogwarts years reading rather than playing with other children. He arrived at school already possessing an encyclopedic knowledge of magical history and the Second Wizarding War. At just 14 he was also able to solve a number of security puzzles in the Minister of Magic’s office (the minister being none other than Hermione Granger herself). A brilliant student and lover of books this newest addition to a long Slytherin tradition could redeem the house all on his own.
Regulus Black
Again the Black family enters the list. It’s harder to discuss the brilliance and success of Regulus than it is to discuss his cousin Andromeda’s. He was always closed off, secretive (especially with his brother Sirius) but that, perhaps, was part of his brilliance.
Regulus Black remains one of the only characters ever, and one of only two Slytherins, to outsmart Voldemort himself. When Dumbledore and Harry go searching for Horcruxes not even they are prepared to find the forgery this lesser-known Black brother left behind. As Regulus writes, "To the Dark Lord, I know I will be dead long before you read this but I want you to know that it was I who discovered your secret. I have stolen the real Horcrux and intend to destroy it as soon as I can. I face death in the hope that when you meet your match you will be mortal once more. - R.A.B.”
Leta Lestrange
A few generations removed from our better-known heroes, Leta makes her presence known in the new Fantastic Beasts and Where to Find Them franchise. A close friend of Hufflepuff's Newt Scamander, Leta was a Slytherin who took to reading and experimenting due to the bullying she suffered, even as a member of the stereotypical “evil house.” She grew into a successful Ministry official, working for the Department of Magical Law Enforcement. What she is best known for is her bravery, in facing Gellert Grindewald. Thinking on her feet, Leta is able to distract the dark wizard, giving Aurors and both Scamander brothers, a chance to escaped destruction. Leta was a much more complicated person than a mere Slytherin and was interested in far more than writing her and Newt’s initials on a Hogwarts desk.
Phineas Nigellus Black
One of only two Slytherin headmasters in the history of Hogwarts School there’s no question that Phineas Nigellus must have been wise beyond the usual serpent student to make his way to this highest of posts. His unpopularity notwithstanding, he took the position and remained, in portrait form, to advise all those headmasters who came after him. As his portrait makes clear through its snide and sarcastic manner, Phineas did not and still does not take ignorance lightly. He expects those around him to be knowledgeable, just as he is, and will have more than a few words with anyone whose intelligence he sees as beneath his own.
Horace Slughorn
Not a headmaster, but a positions master, Horace Slughorn was a brilliant, if slightly self-centered Hogwarts professor for at least two years. Teaching at all levels, including the N.E.W.T. Potions students, he understood everything about his business. Able to brew everything from simple sleeping droughts to the incredibly complex Felix Felicis, or liquid luck, potion. With a penchant for famous and successful friends, Slughorn has always been a consistent correspondent, wisely keeping his powerful acquaintances close in case he should need a favor. Sometimes brilliance isn’t only about what you know, but who you know, and Slughorn was certainly the expert, and quite the pen pal.
Severus Snape
Here we have both potions master and second Slytherin headmaster, spy and traitor, and hero to the rebellion, Severus Snape. A keen and successful student during his days in Slytherin house, Snape grew to be an even more brilliant adult. Not many wizards can work for both Lord Voldemort and Albus Dumbledore and survive the ordeal for almost two decades. If that doesn’t mean Snape deserves a place in our top three then nothing does. Whether you approve of his treatment of students or not, it is impossible to argue the difference his skills and genius made in the eventual downfall of The Dark Lord. From editing his potions book as “The Half-Blood Prince” in school, to teaching for years, and passing reports to both sides of the way, Snape’s actions and words will never be forgotten.
Salazar Slytherin
It wouldn’t be a true list of Slytherin intelligence if the wizard who started it all was left off. Coming in at number two, Salazar Slytherin, Hogwarts and house founder himself, a parseltongue and a legilimenser, Slytherin understood all too well the importance of language. One of the four most brilliant witches and wizards of his age it takes quite a bit of cunning and smarts to both build and hide a secret chamber beneath the school, and the noses, of the other most brilliant wizards and witches of the age. As The Chamber of Secrets confirms, Slytherin was completely successful in this particular endeavor. Never underestimate a man who is both talented and steadfast in his beliefs.
Merlin
While mostly mentioned as a sort of curse, “Merlin’s beard,” within the Harry Potter books, it was long ago confirmed on J.K. Rowlings Pottermore site that Merlin himself, the most well-known wizard in any part of the world, was, a Slytherin. The man who would grow up to teach King Arthur, who would have the greatest of wizarding orders named after him, “The Order of Merlin,” was from the house of silver and green. No one has done more to popularize magic in the muggle world except perhaps Harry Potter himself. Here’s to all the books of Merlin.