Roronoa Zoro is one of the main characters of One Piece and the first crewmate who Luffy recruited on his journey to become the Pirate King. Zoro's most defining characteristics are his incredible strength, which he continuously hones to be able to surpass the likes of Dracule Mihawk, and his fierce loyalty to his captain.
While Zoro doesn't have any love interests in the story right now, there are lots of characters in the world of anime who would complement his personality and bring the best out of him.
10 Erza Scarlett Is A Talented Swordsmaster Like Zoro (Fairy Tail)
One of Fairy Tail's most intriguing characters, Erza is an S-class mage and a member of Team Natsu. She's known to be tremendously powerful with a strong drive to improve all the time, just like Zoro. Erza has quite a strong personality which is something a person like Roronoa Zoro would enjoy being around. Being a swordsman himself, Zoro would have nothing but respect for her and understand her like no other person.
9 Mikasa Ackerman Is Loyal Like Zoro (Attack On Titan)
Known to be a skilled warrior, Mikasa Ackerman is a menace to all those who threaten to harm her friends. She's incredibly skilled with a blade, just like Zoro, and is remarkably driven by the same feeling of loyalty. Mikasa also has a soft side that she often chooses not to show but with someone like Zoro, who'd understand her struggles, Mikasa would truly be able to be herself and bring the best out of him as well.
8 Winry Rockbell Is A Ball Of Energy (Fullmetal Alchemist)
Fullmetal Alchemist's genius mechanic, Winry Rockbell is one of the most important side characters in the story. She's known to be extremely energetic and, more importantly, strong-willed. Although she isn't a warrior like Zoro, Winry puts all her heart into whatever it is that she's doing, which would resonate with the swordsman of the Straw Hat Pirates.
7 Temari Is A Capable & Prudent Leader (Naruto)
Naruto's Temari is one of the most prudent characters in all of anime and is hardly ever fazed by those around her. She often speaks her mind regardless of who she's up against, giving her a fearless edge.
Zoro carries the same personality traits and would, more likely than not, relish stepping up to someone like Temari. Together, the two would certainly bring the best out of each other.
6 Nobara Kugisaki Would Work Perfectly With Roronoa Zoro (Jujutsu Kaisen)
Nobara Kugisaki is known for her confidence in her abilities and her stern nature, and although she doesn't care about everyone, she's more than willing to stand up for those who she considers dear to her just like Zoro. Nobara is outspoken and would thus be a perfect match for Zoro, the Pirate Hunter. What's more, her great set of abilities makes her strong and someone who Zoro would absolutely love fighting alongside.
5 Nejire Hado Can Get Along With Anyone (My Hero Academia)
A third-year student in My Hero Academia's U.A Academy, Nejire Hado is one of the three strongest students of her generation of Heroes. She's very energetic, capable of talking about the things she's passionate about for hours. She's also very blunt, which is something she shares with Kozuki Hiyori, Zoro's potential love interest in One Piece. Nejire bears a remarkable similarity to Hiyori and she's also strong, making her a perfect match for Zoro.
4 Casca Is A Born Fighter Like Roronoa Zoro (Berserk)
One of the former members of the Band of Hawk, Casca is an incredibly skilled Swordswoman whose abilities follow close behind Guts and Griffith in the story. Casca is a born warrior and has carved her way through every enemy she's ever faced since joining the band.
Interestingly, she's also the love interest of Guts, a character who strongly resembles Zoro in personality. Given how well she fits Guts, she'd be excellent with Zoro as well.
3 San Is A Pure & Powerful Warrior (Princess Mononoke)
Raised by wolves, San is an extremely capable warrior girl who is known to have tremendous strength. She has great proficiency over all kinds of tools, such as daggers, and even spears. San is a kind person who loves fiercely but also won't stand anyone threatening those she loves. On top of everything, she's a spiritually pure character who Zoro couldn't help but be amazed by. Given how similar the two are, they'll definitely hit it off.
2 Rukia Kuchiki Is A Strong-Willed Fighter (Bleach)
One of Bleach's most heroic characters, Rukia is a shield to all those she loves. Her inability to open up properly is very much like Zoro, and she will put her life on the line for those who matter to her if necessary. Everything about Rukia, from her bravery to her skills as a fighter, makes a perfect match for Roronoa Zoro.
1 Kallen Stadtfeld Is An Army Of One (Code Geass)
Code Geass's Kallen is one of the strongest characters in the story, capable of matching the likes of Lelouch and Suzaku in terms of combat. Kallen is caring and fearless but at the same time, ruthless to those who stand in her way. Given her personality, it's quite easy to see that Zoro would be intrigued by her, and the two would love to have each other's backs in combat.