Summary
Shōnen is the most popular subset of manga and anime, enjoying audience appeal well outside its target demographic of young boys. It is well known for its heroes and villains. Oftentimes, the best in either camp tend to have levels in their buildup.
Many great villainsare often teased or encountered extensively before their final fight. However, there are some villains who can manage to leave an impression without as many appearances. Whether it’s their cool powers, interesting narrative progression, or in some cases, a truly well written story. These are some of the best shōnen villains to only be relevant in one arc.

Boros is a devastatingly strong alien, who was foretold of a foe across the galaxy who would be a fitting challenge for him. He has three different forms and has searched across space for his ideal competition. He was excited to finally discover Saitama, but it became something of a pyrrhic victory, followed by an outright loss.
Even so, by the standards of most of Saitama’s foes, Boros was a relatively tough customer. He managed to withstand multiple punches, and wasultimately defeated by Saitamapunching a planet-destroying blast back at him. As the conqueror lays dying, Saitama feels compelled to compliment Boros on his physical strength. Although Boros remains upset that Saitama had strength to spare.

Boros' fight with Saitama serves to lampshade the extent of Saitama’s might. Even other characters who are incredibly strong on a cosmic scale fall to the might of this hero no one knows.
Even amidst the many antagonists ofOne Piece, Enel manages to leave quite a shocking impression.One Piecevillains who take land for their own and oppress its people are common, yet relatively few view themselves as gods. Many in the series are aware of a bigger fish, typically either the World Government, World Nobles, or in some cases, a more powerful pirate.

But ruling over the aerial island of Skypeia, Enel is above all that in the most literal sense. Having defeated the previous ruler, Gan Fall, Enel crowned himself the God of Skypeia. While Enel is not without opposition, part of what makes the “God” aspect feel like less than an honorific is the simple fact that Enel himself largely meets no meaningful opposition for most of the chapter. He leaves the majority of the proper fighting early on to his subordinates.
It is only when Luffy, who is largely immune to the electricity powers conferred by theGoro Goro no Mi, encounters him that his title starts to feel a bit hollow. Even with this massive disadvantage, he still finds new ways to attack Luffy, making use of his lightning and staff to create a makeshift trident with which to stab him.

After his defeat, Enel largely stepped away from the series. Most notably, he was the only established Logia user at the time to not be present at Marineford. Enel was shown to have taken over the moon in a series of mini-arcs which made up a page each in chapters focused on the now separate main story. At the moment, it doesn’t seem likely he’ll return.
Dragon Ball Super
Zamasu seemed the perfect candidate for Supreme Kai. He was intelligent, self-aware, and cared for the balance of nature. Until mortals get involved, then every one of those traits flies out the window. Zamasu’s heavy prejudice against mortals manifested in a single-minded desire to erase everything from every known universe. He wiped every Kai and God of Destruction for not being harsh enough on mortals, and allied with Goku Black (another version of himself, making use of Goku’s body) to terrorize the already-devastated timeline of Future Trunks. His various forms, includinghis “fused” form, manage to be more than a match for Goku, Vegeta, and Future Trunks.
What makes Zamasu more interesting than his psychopathic philosophy is how close he comes to succeeding in his goal of wiping everyone out. Whenever Zamasu is torn apart from damage, he simply regrows himself like the head of the hydra. It takes Zeno, the Omni-King, erasing the entire multiverse to defeat him.

Despite being theBeastarsmanga’s final antagonist, Melon himself had little relevance to the greater plot. That said, his existence as the “love failure” feels like a natural culmination of the narrative’s themes, making Melon represent something greater in the grand scheme.
The greater narrative focuses on breaking down barriers between carnivores and herbivores, and in a way, Melon represents the final challenge; the proper integration of those descended from both. Melon himself is a gazelle-leopard hybrid, who seemingly cares little for either carnivores or herbivores. He was raised by his leopard mother, who took his father’s abandonment of her poorly. She mentioned wanting to eat him, and he responded by murdering her.
Since then, he has largely shown himself to be an amoral figure, who seems to care only for himself. He is introduced as an herbivore therapist, capable of acting calm and kind. However, this is a ruse to kill his patients. He tends to wear a mask over his face, to hide his more carnivorous features. Even so, he continues to grow spots which he covers up with tattoos of melons. While his vicious behavior is in line with the perception of carnivores, he ironically seems to hate his carnivore side.
A microcosm of his character would perhaps be both ordering a meal for a carnivore and one for an herbivore. He eats them both and says they taste like sand. Even though Melon is apprehended, the greater problem he represents remains.
The ending of the story makes it clear that this is but a footnote in their current society.Legoshi and Haru commiserate, but are briefly stopped by the authorities presuming he is assaulting her. This makes it clear that the integration of carnivores and herbivores is, despite our heroes' efforts, still not the norm.
The mightiest spawn of the Chimera Ant Queen, Meruem proved himself to be absolutely fearsome in his own right. The very process of birthing him caused severe pain for his mother. Meruem is shown to be ruthless in battle,effortlessly executing “friend” and foe alike. He stakes his claim to be King of the Chimera Ants, declaring a war on humanity.
He seeks to further expand his prowess by being a champion of strategy games. He soundly beats the champions of chess, shogi, and go. However, the gungi champion, a blind girl by the name of Komugi, proves a bit more difficult. After taking some time to adjust to her disabilities, Meruem discovers she has forced him into a situation he cannot win. He asks for a rematch, and loses again. Meruem finds the loss amusing and seeks further ways to disrupt her rhythm. He continually attempts to win, failing every time. Meruem’s games with Komugi allow him to have more respect for humans, compounding his complicated feelings as a human-chimera ant hybrid. Although few humans have his love and respect quite on the way Komugi does.
Eventually, Meruem grows more and more attached to Komgui. After being infected with a contagious poison and left near death, he asks Komugi to play one final gungi game with him. She agrees, and refuses to leave, even after learning of how contagious the poison is. The pair die holding hands. Meruem is a fascinating antagonist, managing to pair his excellent power with a bit more depth as he gains love and respect beyond the fear he had amassed.