Most fans will be quick to say that an anime can't reach the next level without a good villain—one that drives the main character to become better and gives viewers a reason to want to see them lose. Shonen anime is well aware of this, so they often introduce characters that are so powerful they feel unfair.
In a genre where the heroes can randomly grow stronger in the middle of a fight, it can be argued the villains often need to be ridiculously strong just so the main character can have a challenge even after they've gained their power-up or transformations. Here are 10 of the strongest villains in the genre, ranked by power level.
10 Muzan Has Incredible Regeneration, But Only Fights Humans
Muzan suffers from Big Fish, Little Pond syndrome. He’s incredible when he’s bullying humans who’ve learned to develop weapons and fighting styles to battle him. And to his credit, he’s got reaction time and the attack power to bring down anyone just short of superhuman, so he's capable of beating the main characters. But anything higher level than that and likely it'd be a bit of a problem. The character is consistently shown to be incredibly powerful, even amongst the other demons that he's created—however, once he was challenged, he had no answer for the person in question.
9 Dio Brando Is Capable Of Stopping Time
Dio Brando is transformed into a vampire early on in JoJo’s Bizarre Adventure, and he becomes the primary villain for the group for quite some time. As a vampire, he’s got the speed and strength that can take out even skills Hamon users. Later, he takes over Jonathan Joestar’s body and becomes even more powerful, learning how to use a Stand. His special Stand, The World, can stop time for him, and because he’s not alive, he can do it for long periods of time, making him all the more dangerous.
8 All For One Battled The Symbol Of Peace
All For One has the unique ability to be able to steal Quirks from people. The character single-handedly brought about an age of darkness and was able to fight All Might himself to a standstill. The fact that he can fight on All Might’s level alone makes a statement: All Might has powers equal to a Golden Age Superman, with him being able to alter the weather from the wind of a single punch. That level of power makes him hard to bring down, and the ability to steal someone else’s powers and add them to his own adds unpredictability.
7 Zagred Caused The Magic Knights And Elves To Unite
The final villain of Black Clover’s Eye of the Midnight Sun arc. This character winds up being a creature from another realm, one that wields the power of multiple different kinds of magic. With his abilities, it isn’t enough to have Yami and the other Magic Knight Captains around. Even the elves have to pitch in, and it’s only with Asta’s anti-magic that they stand a chance. This immense power is something few magic knights could hope to keep up with.
6 Mereum Took An Entire Nuclear Weapon To Stop
Hunter x Hunter’s version of Cell. This character was truly terrifying, as the Chimera Ant King had discovered the power of Nen and thus developed his own Nen to make him even stronger than he was supposed to be.
Mereum’s power was so great that he faced the Hunter Association's genius and still managed to defeat him. In the end, the only thing Netero was able to do was to drop a nuclear bomb on him, and even that didn’t finish him initially.
5 Sensui Was So Powerful He Could Wipe Out Monsters At Birth
The last real villain of Yu Yu Hakusho—Sensui was the Spirit Detective before Yusuke. This is the rare time where the villain actually won. Yusuke tried to defeat Sensui, but he wasn’t strong enough. Despite his training, despite gaining Genkai’s power, despite tapping into all his best abilities—none of it mattered. Even with the power of his newer form, it simply wasn't enough to overcome Sensui. In front of Sensui, he was out-powered and outclassed in hand-to-hand combat. His friends couldn’t even save him. As an S-Class fighter possessing Sacred Energy, his primary limitation is that he’s sick when he first appears.
4 Acnologia Nearly Destroyed The Entire Fairy Tail Guild
Acnologia was first hinted at when they introduced Fairy Tail’s Gildarts, the S-Class mage who was often so powerful he had to be kept off-camera not to have him win every fight. Gildarts lost his limbs trying to fight Acnologia and didn’t scratch him. His first appearance saw him obliterate Fairy Tail’s Tenrou Island base and nearly take out all of Fairy Tail with him. After he met a Dragon Slayer boasting eight Dragons' powers, he killed him in seconds and continued his rampage. He was only able to defeat Fairy Tail, separating his mind from his body and sealing off the body while defeating the mind.
3 Madara Uchiha Battled Against The Entire Ninja World
Naruto fans everywhere insist Madara is one of the strongest anime villains ever to walk the Earth, and it’s difficult to argue otherwise. A founding member of Konoha Village, Madara was a genius ninja with powers that allowed him to fight for a full day without rest. Boasting both the Rinnegan and the Sharingan are the beginnings of all the things he’s capable of. Madara’s key accomplishment involves beating down pretty much everyone.
2 Aizen Can Manipulate The Perception Of Reality
Aizen isn’t the final boss of Bleach, but he’s the reason the final boss lost. Aizen has plans upon plans, and even when things don’t go his way, he can orchestrate them to do so. But what makes Aizen really dangerous is his Shikai.
Kyoka Suigetsu’s power is to take over someone’s senses completely and utterly. There are no limits to this ability. It doesn’t matter if the person is stronger. It doesn’t matter that they know about the ability. Once they’re trapped in it, there’s nothing they can do about it. For this reason alone, it’s difficult to see anyone ever beating him.
1 Jiren Pushed All Of Universe 7 To The Limit
The strongest opponent Goku had ever fought up to that point, Jiren is the man on the level of the gods of destruction. The anime drove home just how hopeless anything but the best was against Jiren. Super Saiyan wasn’t even noticeable. By Super Saiyan 3, Jiren thought it was worth blocking. Super Saiyan Blue was only slightly worth acknowledging. Jiren embodies strength, and it’s that strength that allowed him to defeat everyone short of Goku in his perfected Ultra Instinct form.