The Shadow Realm is a euphemistic expression specifically designed by 4Kids for the English dubbed version of the Yu-Gi-Oh anime. It is especially used as a euphemistic expression of death. It is referred as a dark other dimension in the Yu-Gi-Oh! series that was a place of suffering where people could be sent to. When a death would occur in the Japanese version, it would usually be censored in the English version to say he/she is sent instead to "Shadow Realm" (Though there is little difference, since the Shadow Realm is supposed to be Hell and the soul still leaves the body upon banishment.) The concept is also mentioned in the Yu-Gi-Oh! GX anime.
The Shadow Realm as presented in the English-language version of the anime does not exist in either the original Japanese-language Yu-Gi-Oh! manga or anime series. However, the concept is based on an occasionally mentioned place called the World of Darkness (Yami no Sekai). This was where the soul of Solomon Muto was placed after being absorbed into a "Soul Prison" card by Maximillion Pegasus. This World of Darkness was also mentioned by Titan in the Japanese version of Yu-Gi-Oh! GX. He was taken there after losing to Jaden. Here he met Kagemaru, who gave him his Shadow Charm mask, letting him return to Earth as one of the Shadow Riders. He would Duel Alexis Rhodes, one of the holders of the Spirit Keys. His intent was defeat her drag her to the World of Darkness, just as her brother Atticus Rhodes had previously been. However, he would lose to her and be dragged back to the world himself.
The Shadow Realm is often connected to Millennium Items, and the alternative dimension in which Shadow Games take place is also referred as the Shadow Realm. The Pharaoh used the power of the Millennium Puzzle to "Mind Crush" Ghost Kaiba (twice), Panik, and a mugger, banishing them to the Shadow Realm. Pegasus used his Millennium Eye to take both his duels with Yugi to the Shadow Realm, and to imprison Grandpa, Mokuba, and Kaiba in cards. Bakura also used his Millennium Ring to initiate a few shadow duels, and to trap some victims in the Shadow Realm. Marik Ishtar also trapped the minds of his Rare Hunters in the Shadow Realm with his Millennium Rod when they lost a duel, and set up some duels in which the loser's soul would be banished to the Shadow Realm. Yami Marik used his Millennium Rod to create shadow duels as well and trap Mai in the Shadow Realm.
Zorc, created through the darkness and negative thoughts inside the human hearts, is also said to be the one who created the Shadow Realm. In ancient Egypt, duelists wore a diadankh around their arm whose energy would be depleted if they took damage from a monster, and if their diadankh energy was depleted, their soul would go to the Shadow Realm, but could still be released.
The Shadow Realm made the event of death and destruction less impacting, by suggesting that an entity banished to the Shadow Realm can come back.
Excluding those who merely duel in the Shadow Realm, as visitors.
- Marik's Father - Banished to the Shadow Realm by Yami Marik.
- Mugger - Soul banished to the Shadow Realm by Yami (the Pharaoh Atem) with a Mind Crush.
- Solomon Muto - Soul trapped in a card by Maximillion Pegasus. He was later released.
- Ghost Kaiba - Banished to the Shadow Realm by Yami (the Pharaoh) with a Mind Crush, when he was Kaiba's dark side. He was later revived by Pegasus, and banished a second time by Yami, this time for good.
- Panik - Banished to the Shadow Realm by Yami with a Mind Crush.
- Mokuba Kaiba - Soul trapped in a card by Pegasus. He was later released. His soul was imprisoned in the Shadow Realm again, this time by Yami Bakura, but was later released.
- Paradox Brothers - It is possible that Pegasus banished them to the Shadow Realm for their failure. However, this is untrue as they duel both Jaden Yuki and Syrus Truesdale in early in the first season of Yu-Gi-Oh! GX.
- Seto Kaiba - Soul trapped in a card by Pegasus. He was later released.
- Bandit Keith - It is possible that Marik banished his soul to the Shadow Realm after regaining control of his mind.
- Seeker - Soul trapped in the Shadow Realm by Marik after losing a duel to Yugi.
- Arkana - Soul presumably trapped in the Shadow Realm by Marik after losing a duel to Yugi.
- Strings - It is possible that Marik trapped his soul in the Shadow Realm, even though he was possessing him for the entire duel.
- Umbra - Soul presumably sent to the Shadow Realm after being defeated in a duel by Kaiba, as the glass which acted as a shadow barrier broke when his life points reached zero. He did manage to save his body with a parachute, however.
- Lumis - Soul presumably trapped in the Shadow Realm by Marik after losing a duel to Yugi.
- Bonz - Trapped in the Shadow Realm by Yami Bakura after losing a duel to him.
- Sid - Trapped in the Shadow Realm by Yami Bakura.
- Zygor - Trapped in the Shadow Realm by Yami Bakura.
- Mai Valentine - Soul trapped in the Shadow Realm by Yami Marik after losing a shadow game to him. Was later released.
- Bakura Ryou - Imprisoned in the Shadow Realm after Yami Bakura lost a shadow duel to Yami Marik. Yami Bakura escaped this fate by hiding in Yugi's Millennium Puzzle. He was released when Yami Marik was destroyed.
- Weevil Underwood - Soul was temporarily trapped in the Shadow Realm by Yami Bakura.
- Rex Raptor - Soul was temporarily trapped in the Shadow Realm by Yami Bakura.
- Karim - Gave all his energy to Shada, depleting his diadankh energy. Was later released when Yami Bakura and Zorc were destroyed.
- Aknadin - Destroyed by the Blue Eyes White Dragon, trapping his soul in the Shadow Realm. His soul was later released, although his body seems to be destroyed.
- Hasan - Diadankh energy depleted when he jumped in front of the guards to protect them from Zorc's attack. His soul was presumably released, but his body was destroyed by Zorc when Shadi took possession of it.
- Shada - Diadankh energy depleted when he jumped in front of the Pharaoh to protect him from Zorc's attack.
- Isis - Diadankh energy depleted when Zorc destroyed her Winged Dragon Guardian of the Fortress. Her body may have died from the resulting fall, but her soul was released when Zorc was killed.
- Shimon - Diadankh energy depleted when Zorc destroyed Exodia. Was later released.
- Priest Seto - Diadankh energy depleted when Zorc destroyed his Blue Eyes. Was later released.
- Yami Bakura - He merged with Zorc but Zorc was killed by the Creator Of Light, thus it killed Yami Bakura.
- The Shadow Realm is believed by many to be Hell. Which is ironic considering it was created by the dub as a means of censorship. As such, banishment to the Shadow Realm is considered to be the same as eternal damnation (although revivable). If one's soul is banished to the Shadow Realm, their body is left in a catatonic state, giving this an undeniable similarity to the Ghost Rider's Penance Stare.
- Interestingly enough, the Japanese version has Bakura sending Bonz, Sid, and Zygor directly to hell as hands pull them into the ground. In the dub the hands are replaced with shadowy clouds.
- Although most of Marik's duels which threatened the loser with outright death were replaced with banishment to the Shadow Realm, Yugi's duel with Joey which threatens to drown the loser is uncensored.