Goku (Dragon Ball) single-handedly defeated the Red Ribbon Army as a child. Ever since then, he has increased in both strength and power. His skills, Ki-based abilities, and Super Saiyans transformation allowed him to overcome the strongest of opponents throughout his life.
Much like his rival, Goku, Vegeta (Dragon Ball series) is a very powerful Saiyan warrior. His energy based attacks, physical techniques, and Super Saiyans transformations have allowed to defeated countless enemies.
Monkey D. Luffy, Roronoa Zoro, and Vinsmoke Sanji (One Piece) are the three strongest members of the Straw Hat Pirates. They are capable of defeating an army of pirates, marine soldiers, giant monsters, and are able to destroy three Pacifistas when it took the entire crew at their best to only defeat one two years ago.
Rob Lucci (One Piece) is physically one of the strongest characters of the series. At the age of thirteen, he killed over 500 soldiers and a crew of pirates single-handedly. And thanks to his training in the Rokushiki and Devil's fruit ability of Neko Neko no Mi: Model, Leopard, his great speed, strength, reflexes, and durability were even enough to bring Monkey D. Luffy to his knees.
Kizaru (One Piece) single-handedly captured 500 pirates during his attack on Sabaody Archipelago.
Every member of the Blackbeard Pirates (One Piece) are extremely powerful fighters, ableto decimate entire countries...
...particularly their leader Teach, having become the Devil Fruit user of the Yami Yami no Mi and Gura Gura no mi has made him potentially the strongest man in the world.
Amande (One Piece) is a powerful master swordwoman,…
…able to massacre an entire army of armored knights single-handedly.
Vinsmoke Judge (One Piece) is the supreme commander of the Germa 66, and is a immensely powerful warrior in his own right.
The yellow flash Yondaime Hokage, Minato Namikaze (Naruto). If he's so much as spotted anywhere near the battlefields, the enemy will sound the retreat.
Sasori (Naruto) is a powerful ninja and a cunning one at that. The use of his puppets have allowed him killthe Third Kazekage and destroy an entire nation.
The Six Paths of Pain (Naruto) were known for the destruction of the Hidden Leaf Village.
Sasuke (Naruto) is dispatching an army of Samurai with his Sword of Kusanagi: Chidori Katana.
Madara Uchiha (Naruto) is a very powerful shinobi who uses his ninjutsu to annihilate most of the relatively undamaged Fourth Division. It was strong enough to bring 5 powerful Kage to their knees.
Erza Scarlet (Fairy Tail), alias Titania. She defeated 100 high-level monsters in a row, which was considered impossible, even for the best.
Acnologia (Fairy Tail) who is considered the King of Dragons possess ludicrous power that he is greater than the entire formidable armies of Alvarez and Ishgar and the mighty Wizard Saints and the dreaded Spriggan 12
Natsu Dragneel (Fairy Tail) is a top class Fairy Tail member and the strongest demon from the Book of Zeref, his strength is so insane he can take down over 900 highly trained soldiers with just one breath attack.
Hattori Zenzō (Gintama) single-handedly taking down the entire Kiheitai fleet with his immense ninja techniques alone.
Afro (Afro Samurai) is an incredibly talented swordsman. He is strong enough to cut through multiple thugs and warriors quickly and effortlessly.
Kenshin (Rurouni Kenshin) the battosai can dispatch several opponents with little effort only with his sheath.
Due to his proficiency with ATs, Agito (Air Gear) can single handedly defeat and kill many adversaries.
King Bradley (Fullmetal Alchemist series) is a very powerful Homunculi. He possesses inhuman skills in swordsmanship that allow him dispatch countless soldiers as if it were a mere sport.
Guts (Berserk), the "Hundred Man Slayer".
Sun Seto (My Bride is a Mermaid) is skilled in swordplay to the extent that she was able to take on and defeat a rival yakuza gang by herself.
Hayato Furinji (Mighiest Disciple Kenichi) is the ultimate one-man army, able to take on an entire miltary base all by himself and win, as well as use humans like shurikens and strong enough to defeat tanks by himself, all while fighting with his eyes closed and only using 0.0002% of his full power
Honoka (The Third) once destroyed an entire army all by herself with just a single swing of her sword
After years of training, Kenshiro (Fist of the North Star) can easily kill several humans without taking a single hit.
Saito Hiraga (Zero no Tsukaima) is the current incarnation of Gandalfr: The Left Hand of God. Being Gandalfr grants him incredible physical capabilities and innate mastery of all weapons, allowing him to single-handed fight an army of 70000.
Cao Cao (Highschool DxD) Hailed as the Strongest Human, Cao Cao is a powerful fighter and the wielder of the True Longinus,being able to fight the most powerful supernatural beings.
Vali Lucifer (Highschool DxD) is thedescendant of Satan Lucifer and the wielder of the Divine Dividing, Azazel stated Vali is the most powerful White Dragon Emperor to have ever existed.
Issei Hyodou (Highschool DxD) wielder of the Longinus Boosted Gear, through constant intense training Issei became a extremely powerful fighter, able to fight the most powerful supernatural beings from a Super Devil to a Evil God and even one of the strongest Evil Dragon.
Kurumi Tokisaki (Date A Live) is a immensely powerful S-Class Spirit being capable of singlehandedly wiped out an army of DEM Wizards and Bandersnatch robots.
Dulio Gesulado (Highschool DxD) is the Strongest Exorcist of the Church.
Sairaorg Bael (Highschool DxD) wielder of the Longinus Regulus Nemea and a extremely powerful martial art master.
Esdeath (Akame Ga Kill) is hailed as the strongest warrior of the Empire, able to fight alone an army of one million men and ten Teigu users.
Aizen (Bleach) is one of the most powerful Shinigami ever known, able to singlehandedly defeat multipe Shinigami Captains without using his full strength.
The Vizards (Bleach) are highly skilled and experienced Shinigami Captains and Lieutenants, and with their new found hollow powers they can annihilate armies of Gillians.
The First Shinigami Captains (Bleach) were noted to be the strongest generation of Shinigami warriors in the history of the Gotei 13...
including Genryusai Yamamoto who is hailed as the strongest Shinigami of all time...
and Yachiru Unohana, the diabolical master swordswoman who mastered eight thousand schools of swordmanship.
Papillon (Buso Renkin) turned to be a deadly fighter once becoming a humanoid homunculus, having devoured his household's entire yakuza security staff and defeated the likes of his more experienced great-great grandfather Dr. Butterfly and the seasoned warrior Genji Ikusabe.
Rei Ogami (Code:Breaker) was able to kill entire armies of hoodlums, yakuza, corrupt policemen, and military-trained personnel with his blue flame.
Toki (Code:Breaker) obliterating an army of military-trained guards with his magnetism, easily deflecting their bullets back at them...
...or using his deadly marksmanship to snipe them down at tremendous precision and distance.