Saitama's physical attributes are off the charts; he has strength, speed and reflexes that far exceed anyone or anything he faces. The world of One-Punch Man is packed to the brim with superheroes, super villains, superpowered monsters and advanced fighting cyborgs, yet with one punch Saitama can defeat them all. 

Alucard is a powered-up version of the legendary vampire Lord Dracula. He's a servant of the Hellsing organization and is meant to act as their sword and shield against enemy factions and the undead. He's invulnerable to conventional weapons, and can dispatch enemies with his two handguns, or by shapeshifting into bats, dogs and other beings. At his full potential Alucard is immensely overpowered - not even the sun can hurt him.

In the real world Kirito is an average high school student, but when he dons the nerve gear headset to dive into a virtual MMO he becomes nearly unstoppable. Armed with superior gaming instincts, a cool head in any situation and a unique duel wield skill Kirito is able to navigate any gaming challenge even - when his favorite MMO turns into a life or death struggle to escape the game.

Lelouch Lamperouge is an incredible and gifted strategist. Coupled with his ability to make anyone do as he says, Lelouch can do almost anything he puts his mind to - even take down an empire.

Kenshiro is master of the Hokuto Shinken style, a martial art that targets pressure points to lethal effect. Kenshiro is such an effective killer than his opponents don't even realize they're dead until Kenshiro says his catchphrase Omae wa mou shindeiru! (You're already dead!) Kenshiro's opponents are dead the moment they decide to fight him, it just takes a bit of time before they catch on to the fact.

Kenshiro's older brother Raoh was also trained in the deadly art of Hokuto Shinken, but Raoh uses this powerful martial art to become a brutal conqueror. Leading an army of martial arts warriors Raoh is able to dominate and crush any foe in his way.

When the servers for his favorite MMO are about to be shut down Momonga mysteriously wakes up in the game world. There, he's virtually a demigod due to his intimate knowledge of all of the game's mechanics and his being armed with all the highest level spells and legendary gear. Momonga is so far above every NPC in the game that he often doesn't even bother using his magic, but instead beats everyone with ease while masquerading as a melee fighter.

Nicknamed "The Humanoid Typhoon", Vash the Stampede is classified as a natural disaster due to the calamities that occur everywhere he goes. Vash is a master gunslinger with superhuman speed, reflexes, eyesight and muscle control - and he never misses his mark. He's so fast that he can dodge bullets at close range or even throw rocks to knock bullets off their course. The only thing that stops Vash from being as destructive as his nickname implies is his desire to walk a path of peace.

Flesh eating zombies are one of horror's most well known monsters, but Attack on Titan upped the ante by making the zombies giants called titans. In a world where it takes an entire squadron of highly trained soldiers to take down a single titan Mikasa and Levi cut through the monsters like a knife through butter. Although they're both normal humans they possess speed and reflexes that allow them to fight the titans on a different level from the rest of the army.

Light Yagami and L are so much smarter than everyone else that they almost seem omniscient at times. They're always able to predict what someone is going to do next - it's like everyone in their world is playing checkers and these two are playing a high stakes game of chess.

Over the course of his life Dio Brando gained a laundry list of bizarre powers, the most powerful of which are his vampiric immortality, his ability to insert pieces of himself into others to make them his slaves, and his Stand The World. The World possesses great strength and speed, but its strongest attribute is the ability to freeze time. If Dio can't beat an opponent with these powers then he'll gladly just drop a steamroller on their head. 

Unlike the majority of the characters on this list, Sakamoto's specialty is stylishly avoiding conflict. No matter how people try to push him, Sakamoto is so far above it all that he barely has to make any effort to shrug them off. No matter the situation Sakamoto is always cool, cooler, coolest.

Love Machine is an exceptionally intelligent AI that sees conquering OZ and stealing millions of users' accounts as nothing more than a game. With a menacing, toothy grin, it defeats other avatars without breaking a sweat and absorbs their data in the process, evolving each time into something more powerful.

Popee lives in the most demented and violent circus to ever exist. His nightmarish existence is filled with danger around every corner: an impossibly sexy clown with a chainsaw, a sentient car driven to run him down. an alien constantly trying to dissect him, and a dog-man best friend that will try to kill him for a drumstick are just a few of the threats that he faces every day.

Despite all this terror Popee is undeniably the scariest part of his world because he meets all of these threats head on and manages to out-crazy them all. Unable to die and armed to the teeth with knives, guns and bombs, Popee meets every challenge with insane amounts of violence. Humanity is lucky that Popee's circus is far away from civilization because he would destroy it with ease. 

Kyuubi is a beast that's well-known and feared throughout the ninja lands. Had it not been for the Fourth Hokage's sacrifice of his own life, Kyuubi would have utterly destroyed Konoha and all its inhabitants. Out of all the Tailed Beasts, Kurama is often regarded as the most powerful. The citizens of Konoha know its power well enough, as they still it even after it was sealed.

Orochimaru was once the prodigy student of the Third Hokage and part of a legendary three-man team; his name is known throughout the ninja world in infamy. After turning his back on his home village and the rest of the world, Orochimaru strayed down the path to immoral and forbidden techniques in order to achieve immortality and everlasting power. He knows no bounds and will do anything to reach his desires. Although he is occasionally seen taking a beating, he doesn't know how to stay down; he always seems to shed his wounds and return, much to the horror of his opponents.

As a child, Itachi Uchiha was a respected prodigy. Later as an teenager, he became wanted for massacring his clan, sparing only his little brother. He wields the Mangekyou Sharingan, and is capable of unleashing its full abilities, something only a select few of the Uchiha could do. With his eyes, remarkable intellect, and eerily collected composure, not many are eager to take him on. Despite his crimes, his skills are highly praised, and feared, by some of the most powerful shinobi in the world.

Kyuubi, Orochimaru and Itachi are OP in the Shippuden series as well (see their descriptions in the above Naruto writeup).

Madara Uchiha is a legend in the ninja world, with abilities far outclassing others, even his own clansmen. Co-founder of the first and most powerful ninja village, which lead to the current modern world, he was also once the leader of the famous and elite Uchiha clan.

Pain is also OP. Wielding the rare and highly regarded Rinnegan eyes, he is believed to be the bringer of world peace. His unique control over the Rinnegan grants him earth-shattering abilities, rendering almost all his opponents unable to land even one blow. Highly charismatic, Pain is strongly worshipped and considered a "God" by those who follow him.

Geist was genetically engineered to be the perfect killing machine. With enhanced physical attributes and intelligence, Geist is instantly a master of any weapon he finds. He can just as easily destroy any enemy that comes his way as he can make the perfect, manly one-liner.

Geist meets another genetically-engineered killing machine named Krauser. Much destruction ensues as the two fight, while anyone that comes between them is cut down like tissue paper.

Born to a family that belonged to the Demon Hunter Organization, Shiki Ryougi was rigorously trained in combat since she was a child. Proficient in hand-to-hand combat and swordplay, Shiki's combat abilities are bolstered by her Mystic Eyes of Death Perception, which allows her to see the best way to instantly destroy anyone. No matter how powerful the foe, Shiki can easily cut them down.