In the case of Salazar Slytherin vs Voldemort, the Hogwarts founder comes out on top. Tom Riddle may have been the Heir of Slytherin, but it seems like a safe bet to assume that the Dark Lord probably couldn't defeat Salazar.
Is Salazar Slytherin more powerful than Voldemort?
Just exactly how powerful were Godric Gryffindor, Salazar Slytherin, Helga Hufflepuff and Rowena Ravenclaw? Oh, using pure speculation, I would say the greatness of the Hogwart's Founders lay somewhere between not quite as powerful as Merlin, but more powerful than Dumbledore, Voldemort or Grindelwal…
He conquered more of the globe and could perform more advanced forms of magic. He might still be controlling much of the world if it weren't for his greatest weakness — his alleged feelings for Dumbledore. Not only is Grindelwald more powerful than Voldemort, but he's also a more compelling villain.
Unfortunately, Snape never succeeded in killing Voldemort, as he would have to destroy all eight Horcruxes, including Harry himself. So, even though Snape might have been a powerful wizard and Death Eater, killing Voldemort was an impossible task for him.
Harry and Draco were pretty much neck-and-neck when it comes to dueling and wand-related stuff. It was only until Harry got a hold of Snape's diary and channeled his Slytherin tendencies that he was able to win against Malfoy. As a result, he nearly killed Malfoy in The Half-Blood Prince.
She was famously intelligent, having solved most of Harry Potter's mysteries with her quick wit and resourcefulness. Therefore, it is not unimaginable that Hermione could have defeated Lord Voldemort had she had a chance.
Undoubtedly every one of the founders of Hogwarts could hold their own against a wizard of Voldemort's caliber, ending the Salazar Slytherin vs Voldemort debate once and for all. However, aside from Salazar Slytherin, Godric Gryffindor would likely stand the best chance in a duel.
Dolores Umbridge is. She's among some of the nastiest characters in the whole series (along with Fenrir Greyback (ew)). In some ways, she was definitely more sinister than Voldemort.
Harry has his superior defensive magical at his disposal, but Hermione is more skilled in protective charms and enchantments. Either skillset could earn them a victory in a duel.
First on our list is Albus Dumbledore, the headmaster of Hogwarts School of Witchcraft and Wizardry. Known for his wisdom and powerful magical abilities, Dumbledore is respected and feared by many in the magical community.
Snape, Slughorn, Andromeda Tonks, Regulus Black, and Narcissa Malfoy at least. Some more directly and some for longer than others but all played a part. Originally Answered: Is there any Slytherin who left to fight Voldemort? Definitely there were.
When it comes to the area of Transfiguration, McGonagall definitely has the upper hand. But when it comes to inventing spells, the Dark Arts, Legilimency and Occlumency, Snape has the edge. McGonagall is surprisingly skilled in the Dark Arts but not on the same level as Snape.
Of course, circumstances play an important role, as Bellatrix Lestrange manages to kill other powerful wizards such as Sirius Black through her occasionally unfair strategies, but in a proper one-on-one duel, Professor McGonagall would win.
In fact, Ron is consistently weaker than Harry in the books and movies. While Ron is powerful enough to fight by Harry's side, it's pretty clear that Ron's spellcasting falls short of Harry's, and he would lose if they fought for real. Especially if he's using that broken wand of his, held together with Spellotape.
Malfoy is always at the receiving end of Ron's punches or hexes throughout the books. Ron fought and beat so many dangerous Death Eaters than Malfoy and survived. Malfoy sure knows more dark magic than Ron but he can not fight.
It's safe to assume that Draco's hatred of Harry was fueled by jealousy. Although Draco attempted to disguise his jealousy with confidence, it still makes an appearance throughout the franchise.
For example, Peter Pettigrew was in Gryffindor, yet he betrayed the Order of the Phoenix and joined Voldemort; Quirinus Quirrell, a Ravenclaw, also allied himself with the Dark Lord; and (albeit only in an alternate timeline) Cedric Diggory from Hufflepuff would become a Death Eater, whereas Slytherins such as Horace ...
Peter Pettigrew represents the worst Gryffindor in the entire Harry Potter series. Wormtail, as he was known among his friends, was thought to be a friend of the Marauders and a member of the Order of the Phoenix, but he was secretly working for Voldemort and committed the ultimate act of betrayal in the series.
