Affiliation: The Dark Lord, Head of the Death Eaters
Voldemort is the Hater-in-Chief, and he's got all of his many followers drinking his bitter Haterade.
However, there's more to the Dark Lord than pure and simple, black-and-white evil. And Book 7 really brings the loose ends together for us. Here, the slow unraveling of Voldemort's story that began in Book 6, Harry Potter and the Half-Blood Prince, concludes and reveals Voldemort/Tom Riddle to be more complex than your bog-standard, ordinary villain. Yes, we even see some of Voldemort's vulnerable spots – and though our glimpses of him are few and far between, we can learn a lot from his fears, anxieties, and frustrations. Well, let's get into them, then!
First of all, the objects Voldemort chose to make into Horcruxes betray a certain level of anxiety about his own right to be in the wizarding world at all (let alone dominating it). His focus on objects and hiding places – like the Lestranges' Gringotts vault – that have great significance to wizarding history and lineage show us his fervent desire simply to belong. Like Harry, he's an insider who's also an outsider, and can never shake that feeling of exclusion. It's this fear of not belonging enough that fuels some of Voldemort's resentment and hatred of other outsiders, such as half-breeds, non-humans, and Muggles; his desire to eradicate these "impure" elements reflects his obscured desire to rid himself of the traces of impurity in him.
And it turns out to be this very outsider status that undoes Voldemort in the end. Namely, his desire to gain more magical knowledge didn't encompass some of the first things that magical kids learn – the Deathly Hallows. And, thus, Harry ends up with more knowledge than Voldemort has.
Another part of the trouble is that Voldemort seems to view magic simply as a weapon – or, more abstractly, as pure power. His only desire is to accrue even more power (a concern that Harry doesn't have), which ends up being his downfall. Voldemort single-minded pursuit of the Elder Wand simply in the name of world domination proves that he isn't actually worthy of its power, and it just ends up blinding him to other things. His fatal flaw is his belief that being strong is more important than being human – however, unhappily for Voldemort, humanity itself is the most important and powerful trait in the world, as Harry demonstrates.
For more on Voldemort's past, see our analysis of the Dark Lord in Harry Potter and the Half-Blood Prince.