Sharks in anime have taken some interesting roles as characters. It entirely depends on the type of anime in which they appear, be it science fiction, drama, or fiction, with some being more realistic depictions of the species while others are anthropomorphic and cartoony.
Whether or not the following sharks are main characters or take supporting roles is beside the point. Just like in real life, these are some of the best sharks in anime, and they make an impression even if they only appear for a short time. No matter what kind of anime a viewer likes, there will likely be a shark character in it somewhere.
7 Megalo, One Piece
Princess Shirahoshi is one of the side characters allied with the protagonists in the Fish Island Arc of One Piece, and her faithful sidekick is a pet shark named Megalo. He's not only her faithful companion but also her bodyguard, and for those who know the show or anime, he's everyone's favorite shark.
Shirahoshi is the youngest daughter of King Neptune, so she's going to have some solid backup and an oversized shark is perfect. Megalo can even fit Shirahoshi in his enormous mouth if she needs extra protection even though it makes him uncomfortable.
6 Megalodon, A Sister's All You Need
A shark that's a tsundere character makes a lot of sense, and Megalodon fills that role in this unique show about little sisters, writers, and sharks. In nature, the megalodon is an enormous shark, notoriously one of the biggest fish in the sea, and her size is comparable to the whale shark in both real-life and animated form.
Megalodon appears in the first episode of the show which includes the main characters taking a trip to the island of Okinawa for some adventures. The title, "As Long As It's Research" references some field work going on in the ocean that may or may not be work-related. Megalodon appears in this episode along with some other aquatic creatures.
5 Jiromaru, Dororo
Several shark demons appear in Dororo, a strange tale of an orphaned thief and a ronin with no limbs or internal organs. Shiranui, a fisherman who had been orphaned by war, was Jiromaru's master, or at least it seemed that way at first. They are two of the major antagonists of the story.
It sounds sordid, but these are the kinds of demons that accept sacrifices of organs and dismembered body parts, so it makes sense that they would be in shark form. Shiranui earned the friendship of the sharks by feeding them his right arm, and he seems to think it was a small price to pay.
4 Sharpedo, Pokemon
The Sharpedo appears in several different Pokémon episodes, almost always when the ocean or some sea-side location is involved. Just like in real life, they are feared by humans and can be dangerous creatures if encountered in the wild.
The Sharpedo evolves from the Carvanha, which is not a shark but more like a piranha, living in rivers and other bodies of fresh water. It evolves into mega Sharpedo, which has some nasty fun and thorn damage in addition to its decisive and brutal bite.
3 Whale Shark, A Sister's All You Need
The only shark big enough to stand up to the massive Megalodon, the Whale Shark is another character that appears in that special episode of A Sister's All You Need. She's open about her feelings, however, instead of trying to be tough on the outside like her friend.
The Whale Shark appears in the same episode of Megalodon and same plot that involves adventures and "research" while playing in the warm ocean waters off the coast of Okinawa. Unlike her counterpart, she has both a sister and an enemy.
2 Saburomaru, Dororo
Jiromaru didn't work alone. He was one of two sharks that accepted sacrifices in the form of human limbs and other delicious meaty bits. It was assumed that he and Saburomaru were brothers but that was never confirmed, and they didn't need to be.
Although it seemed like the one-armed fisherman Shiranui was their master, he was the one who was beholden to them, believing that sharks were superior to humans. Both of these sharks were also demons in addition to being vicious animals, and when one is slain the other rises up to take revenge.
1 Monda, One Piece
Monda isn't exactly one of the main characters, but a definite fan favorite who has also appeared in the video game franchise. Who can resist those golden stars and that irrepressible grin? As an ally of Capote and a member of the Foxy Pirates, however, Monda is often an antagonist, although the Foxy Pirates do take the side of Luffy and his Straw Hats at certain times.
Aside from being cunning and clever, this character's superpower is his fast swimming abilities. It was mostly because of him that his team won the Donut Race in the Long Ring Long Land Arc, although Foxy's Devil Fruit abilities were also a key factor in their win.