Harry Potter: 10 Most Powerful Slytherin Students

If being scary counts for anything, then there's plenty of reason to consider Barty Crouch Jr. one of the most powerful wizards from Slytherin. This character is freakier than Aragog and his eight-legged kiddies, and he doesn't mess about.

Crouch delved into villainy from a young age, joining up with Voldemort and becoming a Death Eater in his formative years. That probably explains why he's as powerful as he is since he's been working for the dark side since he was a teen.

This follower of the Dark Lord is chaotic but also incredibly sharp mentally. He's intelligent and calculating, which means he has a firm grasp on his ability to cast spells. This makes complete sense, as not just anyone can infiltrate Hogwarts and rig the events of the Triwizard Tournament.

Also, for the record, the movies and books do not outwardly state that Barty was sorted into Slytherin. Despite that, it's still easy to assume that this serpent-like creep was treated to a shade of green from the Sorting Hat, so his position here feels very appropriate.