Berserk's main star is the rugged swordsman mercenary known only as Guts, a battle-hardened warrior who will gladly take on all challengers, may they be humans, Apostles, or anything in between. At different times of his life, Guts tried to adopt a lone-wolf mentality, but in reality, Guts does better when he's in a party, including rivals.
Unofficially, Griffith was like Guts' rival in the Golden Age story arc, and in later arcs, it seemed Guts had no true equal, and certainly no rival to push him along. Now, all that will change, and a variety of Guts-style anime heroes and villains will arrive in the world of Berserk to serve as Guts' one true rival and bring out the best in him.
10 Captain Kenpachi Zaraki Will Duel Guts Anytime (Bleach)
In some ways, Captain Kenpachi Zaraki of squad 11 is the Guts of the Bleach universe, a tough-as-nails swordsman who knows only one thing: war. He wandered the Rukon District's most impoverished and violent regions, sharpening his skills with countless duels until he finally became a Soul Reaper.
Kenpachi is a deadly and incredibly durable swordsman, able to outlast most of his foes in battle while laughing at his injuries. He could be Guts' semi-friendly rival in Berserk, wandering Midland and challenging Guts to see how much stronger Guts has become.
9 Thorkell Will Gladly Face Guts In Battle (Vinland Saga)
The grizzled Viking veteran Thorkell is similar to Bleach's Kenpachi, a powerful, enthusiastic fighter who thinks fighting people is the best hobby in the world. He is always eager to face new challengers, and he'll be disappointed if he ends up killing them too quickly.
Thorkell could certainly keep the Golden Age-era Guts on his toes, stalking Midland with his mercenary friends and challenging the Band of the Hawk's best members in mortal combat. Guts won't find it easy to fend off Thorkell and his twin axes.
8 Ban Can Do This All Day (The Seven Deadly Sins)
Some members of the Seven Deadly Sins would make odd opponents for Guts, such as the curious artificial being Gowther or the lazy, plant-using fairy King, but the immortal melee warrior Ban is a different story. He was Meliodas' tireless rival for years on end, and now it's Guts' turn.
Ban is a fierce but fair martial artist who loves a good fight, and he knows that constant sparring is a fine way to keep his skills sharp. This unkillable warrior would make for a fine rival to Guts in the Golden Age, challenging him again and again across Midland's many battlefields.
7 Akaza Is Guts' New Apostle Rival (Demon Slayer)
The martial artist demon named Akaza may remind anime fans of characters like Grimmjow from Bleach or perhaps Hisoka Morow from Hunter x Hunter. Akaza is a battle-loving fiend who encourages his enemies to do their best so the fight is that much more enjoyable, such as when he clashed with Kyojuro Rengoku.
Akaza isn't as friendly as characters like Ban or even Kenpachi, but as an unfriendly rival, he could push Guts to the absolute limit in later story arcs where Guts is significantly stronger. With his dragon slayer sword and berserker armor, Guts could stand up to Akaza and test his berserker armor for real.
6 Dracule Mihawk Needs A New Challenge (One Piece)
The world of One Piece has plenty of memorable shonen rivalries in it, including the swordsman rivalry between the Straw Hat pirate Roronoa Zoro and the notorious Dracule Mihawk, the world's top swordsman. For years, Dracule seemed to have no equal, but now he'll go up against Guts.
Dracule Mihawk is an extraordinary swordsman, but not even he has faced the dragon slayer before, nor has he seen a Devil Fruit that can do what the berserker armor does. If Dracule ends up in Midland somehow, he and Guts could test each other out a few times to see who is truly the world's greatest swordsman of all.
5 Benimaru Must Defeat Guts To Impress Rimuru (That Time I Got Reincarnated As A Slime)
The OP isekai hero Rimuru Tempest has many allies under his command, including the ogre sworsdman Benimaru, one of his tribe's few survivors. Benimaru now serves Rimuru loyally along with his little sister Shuna, and he could impress them both if he defeated Guts in battle.
Benimaru's superhuman strength and black fire magic will make him a fine match for Guts' dragon slayer sword and berserker armor, and they could clash as rivals again and again to see who's best. Guts would respect Benimaru greatly, but he'd refuse to ever yield to him.
4 Aoi Todo Is Guts' New Brother In Battle (Jujutsu Kaisen)
The burly sorcerer student Aoi Todo doesn't bring any swords or armor into battle, but he doesn't need them, either. Unlike Guts and Casca, Aoi relies on his bare fists and his powerful curses sorcery to win the day, and he can execute moves that would take even Guts by total surprise.
Aoi Todo loves a good rival who can push him, and today, it's Guts. Aoi would ask Guts what his ideal woman is like, and then Aoi would gladly exchange blows with "my brother" in mortal combat time and again. Guts would find Aoi annoying, but he would also recognize him as a true rival to keep him sharp.
In the Golden Age, where Guts was usually in a relatively good mood, he just might put up with the flamboyant Might Guy as a friendly rival who can challenge him like never before. Might Guy could find work in Midland as a bodyguard or assassin, and soon enough, he'll hear about the Band of the Hawk.
Corkus, Judeau, and Pippin wouldn't last that long against taijutsu expert Might Guy in battle, but Guts could give it a try. If Might Guy holds back somewhat, then the two of them could benefit greatly from this respectful rivalry.
2 Jonathan Joestar Will Help Guts Stay Sharp (JoJo's Bizarre Adventure)
Guts doesn't have his own Stand, but in all fairness, neither does Jonathan Joestar, so they will be fine rivals if they ever cross paths in the kingdom of Midland. Jonathan is a powerful and fearless young man, just like Guts, and they could be terrific rivals in the Golden Age days.
Jonathan, just like Might Guy, could find work in Midland as a bodyguard or perhaps a town's chief of security. If he and Guts met, they would wow the crowds with their bare-knuckle matches, and they'd keep meeting up now and then to test each other repeatedly. They're a good match in the boxing ring.
1 Erza Scarlet Must Cross Blades With Guts (Fairy Tail)
Most characters in Fairy Tail have either the wrong personality or the wrong fighting style to be Guts' rival, but Erza Scarlet, the S-ranked swordswoman, is a different story. Erza is tough, honorable, fair, and fearless as a friend and warrior, and she would definitely remind Guts of Casca.
In the Golden Age arc, Erza would also be a sword for hire in Midland, and she would happily face her one true equal, Guts, in one duel after another while the eager crowd watches on. Even Griffith might pick up some new ideas or strategies watching Erza fight Guts in those matches.
NEXT: 10 Things You Should Know About Guts' Dragon Slayer Sword In Berserk