Don’t judge a book by its cover. As much bother as Slytherin house may have caused over the years, we think they have also given the wizarding world far more than you could ever imagine.

We wouldn’t have Hogwarts

First things first. Salazar Slytherin certainly had his flaws, but you cannot deny that Hogwarts would have been only three-quarters done without him. Like it or not, Salazar was the final piece of the Hogwarts puzzle and built the school in harmony alongside Godric Gryffindor, Helga Hufflepuff and Rowena Ravenclaw. If not for Salazar’s distrust of Muggle-borns, that harmony might have lasted a while longer.

We wouldn’t have Ron

Sometimes past actions can have a life-or-death impact on the present. Take the case of Ron Weasley in Half-Blood Prince. Poor Ron nearly choked to death on some poisoned mead in what was probably his worst birthday ever. Although Harry was the one who saved him, it was the annotations from the mysterious Half-Blood Prince that made the difference.

The note ‘Just shove a bezoar down their throats’ left in Harry’s copy of Advanced Potion-Making might have helped him impress Slughorn in Potions class, but that little nugget of information was literally a life-saver. And it was a note written by a Slytherin – Severus Snape to be precise. After all of their classroom altercations, we’re sure Snape would’ve been thrilled to have saved Ron from mortal peril.

We wouldn’t have Ilvermorny

It was thanks to a descendent of Salazar Slytherin that the North American wizarding school Ilvermorny came to be. If Isolt Sayre had been a student of Hogwarts rather than Ilvermorny, we think she’d have been sorted into Slytherin thanks to her ancestry. Although her own longing to be a Ravenclaw may have tipped the scales – we will never know for sure.

Isolt was a classic example that attitudes don’t have to be hereditary. Slytherin house may have produced some of the most pure-blood obsessed wizards, but a descendant of that house’s founder created a school accepting of all magical people.

We wouldn’t have Ginny

Bear with us on this one. Voldemort simultaneously both nearly killed Ginny Weasley and saved her life. In a roundabout way.

During Chamber of Secrets, a diary containing a part of Tom Riddle’s soul fell into Ginny’s hands. She poured her secrets and fears into the eager diary. Under its influence – it was one of Voldemort’s Horcruxes, no less – Ginny released the Basilisk on her fellow students and was eventually trapped in the Chamber of Secrets.

Harry was able to enter the chamber and rescue Ginny thanks to being a Parselmouth – a talent Voldemort accidentally transferred to Harry when he tried to kill him as a baby. Therefore, Ginny would have died if not for this borrowed Slytherin talent.

We wouldn’t have the Order of Merlin

Merlin was one of the most respected and legendary wizards in history. We see throughout the wizarding world that the expression ‘Merlin’s beard!’ or ‘Merlin’s pants!’ are popular exclamations. Now that’s a legacy.

Merlin was also a Slytherin and this great wizard, among his many achievements, is commemorated by the Order of Merlin; a reward system for witches and wizards who had achieved greatness. Show some ambition and moxie, be rewarded – that’s very Slytherin.

We wouldn’t have such advancements in Potions

Although it’s not a guarantee (just look at Crabbe and Goyle), members of Slytherin do seem to have a real knack for Potions. Harry’s two Potions masters, Severus Snape and Horace Slughorn, were both Slytherins.

Both also proved to be exceptionally talented at the craft. Slughorn presumably managed to brew the intensely difficult liquid luck (Felix Felicis), as he told his class that he had taken it twice in his life. And we all know that Professor Snape was a dab hand at creating the intricate truth potion Veritaserum, and many others besides.

We wouldn’t have Harry

Thanks to one particular Slytherin, Harry Potter nearly perished when he was just a baby. But thanks to a couple of others from that house, Harry’s life was miraculously spared. Two shining examples leap to mind, both from the family that seemed to loathe the Boy Who Lived the most: the Malfoys.

During Deathly Hallows, Draco faltered when he was asked to identify a disguised Harry Potter. His hesitance was enough for Harry to get away.

Then there was that spectacular act of mercy from Draco’s mother, Narcissa. When Voldemort cast the Killing Curse on Harry in the Forbidden Forest he didn’t kill him – instead he destroyed the piece of his own soul that had latched onto Harry when he murdered Lily Potter.

Narcissa Malfoy could easily have told the Dark Lord that Harry was alive and playing dead, but she didn’t. Instead she asked if Draco was alive and then lied through her teeth. Without her shock last-minute decision, would Harry have survived? Who knows?

Thanks, Slytherins!