Spirit Partners are Duel Monster Spirits that have human partners. Their partners and any other humans that possess the ability are the only humans who can see and interact with them. It's also possible to have more than one spirit partner. The following characters own or have the ability to sense a Duel Monster in one way or another. They are presumably Ka due to how Winged Kuriboh appeared in a flashback in the manga.
- Yugi Muto has shown the ability to communicate with spirits, though the ability was rarely touched upon. His Spirit Partners appear to be Dark Magician, Kuriboh, and Dark Magician Girl. He may also have some bond with Maha Vailo, as he said this monster is the most like him.
- In Yu-Gi-Oh! GX, he is shown to communicate with Winged Kuriboh.
- Seto Kaiba appears to have Blue Eyes White Dragon as a Spirit Partner. The spirit told him it wanted to fight during the Duel against Ishizu. Kaiba was even willing to sacrifice a God card in order to bring out his loyal servant.
- Rafael was able to see the spirits of his "Guardian" monsters when he lost his Duel to Atem, but this was not fully explained. His Spirit Partner appears to be Guardian Eatos. When he is controlled by "The Seal of Orichalcos" his Spirit Partner is Guardian Dreadscythe.
- Joey Wheeler's spirit partner appears to be Flame Swordsman as it was his Deck Master and he actually turned into him in the Duelist Kingdom Saga in a Shadow Game against Bakura. Red-Eyes B. Dragon also serves as a spirit partner for Joey; the monster is said to have sadness in its eyes at the sight of Joey's brainwashed state.
- Jaden's Spirit Partner in the beginning was Winged Kuriboh. Later on, he can communicate with the Neo-Spacians and Elemental Hero Neos. He is seen with the spirits of other Elemental Heroes as well, but they don't verbally communicate. He uses Super Polymerization to fuse with Yubel and forms a temporary partnership with Honest before returning it to Yusuke Fujiwara.
- Chazz's main Spirit Partner is Ojama Yellow in the anime, in addition to Ojama Green and Ojama Black, and Light and Darkness Dragon in the manga.
- Aster Phoenix unlocks his ability to see Duel Monster Spirits after his third Duel with Jaden, Aster can also sense their presence. Aster's Duel Monster Spirit may be Destiny Hero Dreadmaster; after Aster decisively defeats Jaden, Dreadmaster envelops Aster and mimics his leave as Aster tells Jaden that he cannot hide from destiny. Also, after Aster and Jaden form the Ultimate Tag Team, Aster entreats his Destiny Heroes to see if he still controls destiny, Aster's Destiny Hero Dasher Duel Monster Spirit later calls out to the Neos-Spacians and initiates a move winning them the Duel, and further showing the bond between Aster and his Destiny Heroes.
- Jesse's main Spirit Partner is Crystal Beast Ruby Carbuncle, but he is also able to interact with the rest of the Crystal Beasts, which he considers his family.
- Princess Rose claimed to be able to see Duel Spirits; though no one believed her, Jaden saw a Des Frog in a Prince's outfit following her after their Duel, suggesting that she was telling the truth.
- Chancellor Foster was the original owner of Ojama Yellow before he passed it to Chazz. He could see and hear it, but it is unknown if he could sense other Duel Spirits.
- Yusuke Fujiwara's partner used to be Honest before he was possessed by Nightshroud. However, he later got it back from Jaden.
- Trapper doesn't possess a Spirit Partner of his own (he once did, but it was stolen from him by another, unnamed person), but nonetheless, wields the uncanny ability to not only see, but also trap Duel Spirits.
- Chumley has Des Koala as his Spirit Partner. It's unknown whether he can see other Duel Spirits, but he is at least able to hear them.
- Though Sartorius cannot see visually see nor speak to Duel Spirits, he is able to sense them due to his honed psychic abilities.
- According to Wheeler's doctor, monkeys have higher ability to hear Duel Spirits than humans, which is why he subjected Wheeler to Dueling experiments.
- Yubel may be considered a Spirit Partner, though the relationship she shares is mostly harmful to all who come into contact with her, so this is debatable. Notably, however, she does afford great power to those who ally with her, although she often turns on her allies when she has no further use for them. However, after fusing with Jaden and being freed from the Light of Destruction's influence, Yubel actually became a loyal spirit partner to Jaden.
- In the GX manga, Koyo Hibiki is the original owner of Winged Kuriboh before passing it down to Jaden. He too is able to communicate with his Duel Spirit. Midori, his sister, is also able to see and hear spirits.
- Zane's Spirit Partner is Cyber End Dragon. In episode 83, it was revealed by Sheppard that he had a special bond with the monster's Spirit and Zane stated that he could hear it crying out in pain after destroying it with Cyber Ogre 2.
- Luna's spirit partners are Kuribon and Ancient Fairy Dragon, though she can see the spirits of the rest of her Deck, all of which are spirit monsters such as Regulus and Sunlight Unicorn. She can also speak to the spirits in other Duelists' decks, whether or not that Duelist can see or speak to spirits or not.
- Leo appears to have "Power Tool Dragon" as a spirit partner, as his dragon has often shown concern for him in his Duels. Leo even asked if it was okay in episode 49, and it nodded, showing that the two can understand each other (whether or not they can mentally communicate like Luna outside of a Duel, is yet to be seen). He later revealed himself in his true form, Life Stream Dragon.
- Yusei Fudo appears to have "Stardust Dragon" as a Spirit Partner, as Luna says in episode 41 "Is Stardust saying he'll protect us?" (when she says this, Stardust Dragon moved a little more in front of them on its own).
- Akiza's Spirit Partner appears to be "Black Rose Dragon", which is shown after the Duel in the Divine Temple. After she and Crow defeat Sherry, Crow says in surprise that Akiza's monster protected them, and Akiza says that was what "Black Rose Dragon" wanted.
- Jack Atlas's spirit partner is "Red Dragon Archfiend", Jack goes as far to refer to it as his very soul.
- Astral's and Yuma Tsukumo's spirit partner is Number 39: Utopia as he is the Number most loyal to Astral and Yuma. This is seen in episode 37 when Utopia protected Astral on its own, and in the episode 38 even left the key because of Astral telling him to go to Yuma. Utopia also left the key in episode 74 to help Yuma against Fender. In episode 111 Yuma says that Utopia is their friend who is always there to give them hope.
- Baby Tiragon has also been shown to interact with Yuma like a spirit partner.
- Gagaga Magician and Gagaga Girl may be Yuma's spirit partners, as they are seen interacting in both the Dub and in the Japanese version. In episode 21 (Japanese version only), during the Duel between Yuma and Lillybot, Gagaga Girl calls Gagaga Magician "senpai", which translates to "teacher" or "master". Also, in episode 77, Gagaga Magician tries to intimidate Caswell when the referee calls him out over the Spellcaster's outfit; and later on in the same episode (Japanese version only), Gagaga Girl is called off the game by Caswell, and she walks off, finding Gagaga Magician and running up to him, calling him "senpai" once more.
- Rainbow Kuriboh is also Yuma's spirit partner; he was introduced assisting Yuma in evading Eliphas, and was subsequently frequently used in Yuma's Duels.
- Kite Tenjo's Spirit partner is Galaxy-Eyes Photon Dragon, as it reacts to Galaxy-Eyes Tachyon Dragon and Number 46: Dragluon.
- Mizar seems to have Number 107: Galaxy-Eyes Tachyon Dragon as a Spirit Partner as it reacts to Galaxy-Eyes Photon Dragon and was captured by Mizar in Barian World.
According to Leo Akaba, the Real Solid Vision technology was discovered in the Original Dimension, though it was his idea to introduce the technology to Dueling. When produced with Real Solid Vision the monsters become self-aware and could feel emotion, though the consequences were not understood at that time. It wasn't until the start of the dimension's destruction, that he was reminded that Duel Monsters were said to had souls.
- Yuya Sakaki's spirit partner is Odd-Eyes Pendulum Dragon. He interacts the most with this monster, and like its owner, Odd-Eyes displays a sense of humor in certain situations.
- Yuto has Dark Rebellion Xyz Dragon as a Spirit Partner; it is shown to consent to Yuto giving its card to Yuya, and Yuto later claims to understand its feelings.
- Yugo has Clear Wing Synchro Dragon as a Spirit Partner, as it conveyed its will to him to fight Yuto and his Dark Rebellion Xyz Dragon.
- Yuri has Starving Venom Fusion Dragon as a Spirit Partner. Yuri's connection with his dragon is the least explored of his counterparts, but he claims to understand its feelings.
- Z-ARC's spirit partners were Odd-Eyes Dragon, Dark Rebellion Xyz Dragon, Clear Wing Synchro Dragon, and Starving Venom Fusion Dragon. Z-ARC could hear their voices and understand their emotions, and their anger eventually convinced him to destroy the world and merge with them into the Supreme King Z-ARC.