One Piece isn't exactly a horror anime series. In fact, it leans much more into comedy when it's not focused on big dramatic fights or saddening backstories. With that being said, to translate just how powerful and menacing some characters in the world are, author Eiichiro Oda made sure to give them introductions that were guaranteed to send chills down the spine of any fan seeing them for the first time.

Related

One Piece: 7 Darkest Abilities In The Series, Ranked

One Piece has no shortage of powerful abilities, but these stand out because of their terrifying nature.

In a few cases, some of these characters turned out to be a lot less terrifying than their first scene initially made out, while others have proven to be just as intimidating as the story has progressed. While a character may not be scary in terms of their physical appearance, they can still come across as an unnerving threat due to their combat skills, the way they speak to the characters, or simply due to all the rumors about them that had been heard leading up to their eventual introduction.

6 Mihawk

While Dracule Mihawk's first appearance at the end of the Baratie Arc might not have been scary in the traditional sense, there's no doubt that when this Shichibukai turned up to face Zoro, it immediately had every fan on edge for what he was about to do to everyone's favorite swordsman. By this point, fans had come to realize that Zoro, being the most experienced member of the crew in terms of combat, was the strongest member of Straw Hat pirates, and while this was certainly true, Mihawk still immediately cuts him down to size upon accepting Zoro's duel.

What made Mihawk even more of a terrifying figure was the fact that this was clearly him using barely any of his power, and since the whole concept of the Shichibukai doesn't even come up until later in the story, no one could have known why or how the mysterious swordsman was this powerful. It's ironic that after the timeskip, and even during the Marineford War, Mihawk is depicted as a fairly laid-back and casual character, but during his first appearance, he immediately struck fear into all the Straw Hats.

5 Arlong

When introducing a big bad villain who is going to play the role of the main antagonist for the next arc, Oda loves introducing them as fearsome leaders surrounded by subordinates who seem more than happy with their cruel contributions to the world. This is very much the case with Arlong, but there are a few reasons why the fearsome Fish-Man's first appearance made such an unnerving impact.

Related

One Piece: The Most Pitiful Villain In The Series

One Piece's villains are some of the most intimidating in anime, but one in particular just makes you feel sorry for them instead.

For starters, viewers and readers didn't really have a good idea of what the Fish-Men were by this point, and if they could even be trusted. Additionally, Arlong was clearly shown to have a much bigger frame than the other Fish-Men who also resided in Arlong Park, not to mention his giant nose which looked almost as sharp as Zoro's blades. The fact that Arlong had also taken over his own island proved that he was not to be messed with, and considering how menacing he is depicted in the anime and the manga, it's great that the live-action series also did him justice in this department.

4 Katakuri

Admittedly, Katakuri is briefly shown in the anime donning a dark coat that covers his face and body a little earlier, but it's not until the beginning of the wedding ceremony that fans get an official introduction to the character thanks to Capone. In the lead-up to the wedding between Sanji and Pudding during the Whole Cake Arc, Oda reveals quite a few characters who have traveled from long and far to attend the ceremony, but the scariest character out of the bunch is one of Big Mom's kids, Charlotte Katakuri. The first time Katakuri shows his face, he's casually sitting on the roof of the Whole Cake Château after having fired a jelly bean at an intruder, taking them down with a single shot.

Right after, Capone talks about how terrifying Katakuri is, including the fact that he can see into the future due to his advanced Observation Haki. This is also where we learn that Katakuri has a bounty of over 1 billion Berries which, at the time, made him the most valuable target in the entire series. All of this resulted in one of the most iconic, memorable, and frightening introductions in One Piece, and his battle with Luffy not long after proved why fans were right to be wary upon seeing him for the first time.

3 Akainu

Fans have long theorized that each of the admirals possess their own sense of justice, with Akainu's being "absolute justice" which essentially means that he's willing to stomp every pirate beneath his boots to ensure safety within the world. This has led him to commit some downright despicable acts during his time as a marine, and perhaps the most frightening is shown when Akainu first pops up on viewers' screens during Robin's flashback.

Related

One Piece: 24 Most Overpowered Devil Fruits, Ranked

Devil Fruit users are some of the strongest people in the One Piece world. These Devil Fruit abilities are absolutely overpowered.

Because scholars at Ohara were illegally studying the Poneglyphs and the Void Century, the Marines ordered a Buster Call to attack the entire island, decimating the land and killing everyone who didn't escape. However, upon seeing an evacuation boat full of civilians, Akainu orders for it to be destroyed, claiming that there may be scholars on board who would spread information to the rest of the world. The fact that Akainu wasn't even an admiral by this point demonstrated just how ruthless he would be with more power and authority, something that unfortunately came true now that he is the Fleet Admiral.

2 Big Mom

Big Mom has played a very important role in the story over the last few arcs, but back when the Straw Hats had just entered Fishman Island after a two-year timeskip, fans really didn't know much at all about this gigantic and maniacal Yonko. Her first appearance comes at the very end of that arc when Pekoms, one of Big Mom's loyal subordinates, learns that the sweets that were supposed to be delivered to Big Mom in exchange for protection of the island had been eaten by Luffy himself.

This leads Pekoms and Baron to fret for their lives, explaining that Big Mom wouldn't hesitate to destroy an entire island with her bare hands if she did not get the sweets she so dearly desired. Things become much more creepy as the scene switches over to Whole Cake Island where Big Mom, half covered in darkness, is drooling due to her excitement for the tea party that was happening in the next few days. To satisfy her endless appetite, she even eats one of her subordinates without a second thought. She then grabs a Den Den Mushi, demanding that Fishman Island deliver the sweets by the next morning, because if not, the entire area would be ravaged by her so-called "beasts."

1 Kaido

It's fair to say that the introduction of "the strongest creature among all living things," Kaido, is one of the most epic yet terrifying introductions in One Piece, and maybe, all of anime in general. Before Kaido is even shown on screen, viewers get a narration that goes over just how big and powerful Kaido is, including the fact that he had been captured several times, but every single execution method failed, making him literally invincible.

Fans are then told that the dissatisfied Yonko has even tried to take his own life several times, but is unable to do so because of how immensely strong he is. All of this leads up to the now iconic image of Kaido standing up before Kidd and his new allies after falling from a Sky Island. As he towers over the mere mortals that stand below him, Kaido doesn't have a scratch on his body even after falling from such a staggering height, and as the members of the Worst Generation tremble in fear, it's hard not to feel the same emotions as a reader or viewer.

MORE: Scariest Bleach Characters