Filler is a necessary evil in the world of anime. While modern series are producing less and less of it, older shows have massive stores of filler episodes and arcs. Many of these arcs have villains, and while some of them are awesome, most of them kind of suck.
But which ones are the worst anime filler villains? Chief among them is Mizuki from Naruto, who spent an entire filler arc revealing himself to be a despicable human being before ultimately transforming into a weird, ugly tiger. There's also the Big 5 from Yu-Gi-Oh! who are so indistinguishable from one another that they barely deserve to be referred to as five separate characters.
Whether they bore you to tears or make your blood boil, none of the filler villains on this list deserve praise.
Mizuki isn't actually a filler character - he's the Ninja Academy teacher who steals a scroll and tries to take out Naruto at the beginning of the series. Why is he on the list, then? Because the fillers expanded his character in such a wildly ridiculous way that it's impossible not to include him.
In one of the weirdest filler arcs to appear in Naruto, Mizuki reappears with the ability to transform into anime Tony the Tiger. But instead of enjoying a bowl of Frosted Flakes, Mizuki is off destroying other peoples' lives for basically no reason. The reason he stole the scrolls was to give them to Orochimaru, who promised him infinite power in exchange. Orochimaru had no intention of giving him anything useful, just a potion that would first turn him into a tiger, than into a withered husk.
It was also revealed that Mizuki was once Iruka's childhood friend... sort of. Rather than acting like a real friend, he was surreptitiously attempting to make him as miserable as possible out of jealousy. What was he jealous of, you ask? The fact that people felt sorry for Iruka after his parents were destroyed by the Kyuubi. He wanted that attention for himself.
There are plenty more awful details about Mizuki where that came from, but let's leave it at that. He's the worst.
Burami is less an actual character than he is a walking fat joke. He isn't exactly a villain - rather, he's one of Kiba's opponents in the Chuunin Exams - but he's so unpleasant that it's hard not to include him. The only thing he cares about is cramming as much food into his face as humanly possible, and he fights by exuding toxic sweat, repulsive stenches, and increasing the size of his body. His character is a collection of offensive stereotypes with little else to recommend him.
In her childhood, Daphne had a somewhat difficult experience. She saw a dragon, and none of the adults who she told about it believed that the dragon was real. This somehow resulted in her becoming so obsessed with dragons that she dedicated her life to building artificial ones - and other peoples' lives, too. In fact, her own town was so sick of her that they used an invisibility spell to hide themselves from her - which she stopped them from undoing as punishment. She also punishes her own creations by making them battle each other into oblivion.
Not every villain needs a compelling tragic backstory to be awesome - but failing that, they need to be sufficiently charismatic or interesting. Daphne is none of the above.
Most DBZ fans disliked the Garlic Jr. Saga, but at least Garlic Jr. himself had something resembling a motive. His henchmen, the Spice Boys, have no motive whatsoever aside from obeying Garlic Jr's commands. What's more, they barely put up a fight, and they have names that are only acceptable if they had a side gig as a Spice Girls' cover band.