Orthrus was a two-headed dog and one of the many monsters sired by Typhon and Echidna from Greek mythology. Among his siblings were Cerberus, Sphinx and Chimera to name but a few. Orthrus was the dog of the TitanGeryon, and along with Eurytion, was the guardian of Geryon's herd of red cattle. Geryon, Eurytion and Orthrus were all slain when Heracles was completing the tenth of his twelve labors.
Orthrus appears as a servant of Pazuzu, and worked alongside the partner before she broke away from Pazuzu's control. After reaching the ruins of Tokyo, Pazuzu instructs the protagonist and his friend to meet up with Orthrus at the Princess Hotel and assist him in taking out the partner. During their confrontation with her at Tokyo Tower, the protagonist ends up siding with her, and the friend and Orthrus part ways with the protagonist. Orthrus continues to fight alongside the friend after his transformation into the Dark Hero, but is killed in battle with the protagonist's party.
Shin Megami Tensei[]
"Origin: Greece. A two-headed guard dog as large as a bullock. This dog was kept by the monster Geryon in Erytheia, the island at the world's end. It was killed by Hercules, who came to steal the red cattle that live there."
—Shin Megami Tensei A-Mode DDS dictionary
Shin Megami Tensei III: Nocturne[]
Orthus is the first of the three judges that the Demi-fiend must fight after being arrested by the Mantra Army. The next judge after him is Yaksini and then after her is Thor.
Shin Megami Tensei IMAGINE[]
"A gigantic, two-headed dog, the child of the storm giant Typhon and the half-snake beast Echidna. His body is as big as an ox, and he has the fearlessness and ferocity of a lion. Orthrus guarded the underworld alongside Cerberus, but was also said to guard the herds of the monster Geryon, who lived on the island of Erytheia at the edge of the world. However, he was killed by a blow from the club of Heracles, who came to the island as part of his Twelve Labors. He also fathered the Sphinx, the Nemean Lion, and other monsters with his mother Echidna."
—Shin Megami Tensei IMAGINE compendium
Orthrus appears in the Suginami field and within the gold level instance of Suginami Tunnels and the Nakano Stone Site. He can be contracted during the daytime in Ikebukuro outside the gates of Zoushigiya Cemetery. He appears regularly as a field boss in Suginami and alongside Cerberus and Garm as the final bosses of the Suginami Tunnels Unknown boss rush. He is also one of the mountable demons within the game.
Shin Megami Tensei: Strange Journey[]
"The two-headed dog who protected the titan Geryon's red cattle in Greek lore. Despite his skill as a guard, Hercules killed him in one blow while performing his Twelve Labors."
—Shin Megami Tensei: Strange Journey compendium
Shin Megami Tensei IV[]
Orthrus appears as a boss on the second stratum of Naraku. Flynn is required to defeat it as part of Navarre's challenge to him and Walter.
Shin Megami Tensei IV Apocalypse[]
"The two-headed dog who protected the Titan Geryon's red cattle in Greek lore. Despite his skill as a guard, Hercules killed him in one blow while performing his Twelve Labors."
—Shin Megami Tensei IV Apocalypse compendium
Orthrus can be found in Ikebukuro or evolve from Chimera once it reaches level 50. Orthrus can also teach Nanashi the Fire Breath, Nihil Claw, Eat Whole and Madness Nails skills through its Demon Whisper. It benefits from learning Physical and fire skills. Orthrus will evolve into Cerberus at level 64, provided that Nanashi can control the result.
Shin Megami Tensei V[]
"The two-headed dog who protected the Titan Geryon's red cattle in Greek lore. Despite his skill as a guard, Hercules killed him in one blow while performing one of his 12 great labors."
—Shin Megami Tensei V lore
Devil Summoner: Soul Hackers[]
"The two-headed dog who, along with his master Eurytion, protected the Titan Geryon's red cattle in Greek lore. When Hercules went to claim Geryon's cattle for his tenth labor, he slew Orthrus with one swing of his club."
—Devil Summoner: Soul Hackers 3DS compendium
Devil Summoner: Raidou Kuzunoha vs. The Soulless Army[]
"The two-headed dog who protected the titan Geryon's red cattle in Greek mythology. Despite his prowess as a guard, Hercules killed him in one blow while performing his Twelve Labors."
Orthrus appears in Dark Tsukudo-Cho as a random enemy and is a bit of a powerhouse being nearly double the level of the next highest level demon in the area. His attacks are short reach, so staying out of his swiping or Maragi spell range will keep him from taking huge chunks of Raidou's HP with each attack. Recruiting an Azumi in the area will allow him to be defeated quickly once the Bufu skill is acquired.
Orthrus will appear again while walking in Ginza-Cho but should be more manageable.
Devil Summoner 2: Raidou Kuzunoha vs. King Abaddon[]
"The two-headed dog who protected the titan Geryon's red cattle in Greek mythology. Despite his prowess as a guard, Hercules killed him in one blow while performing his Twelve Labors."
—Raidou Kuzunoha vs. King Abaddon details.
Orthrus is a demon of the Pyro Order and is one of the rarer demons to appear in the Tento Woods. He can be a potential source of Pyro Bronze to further upgrade Raidou's weapon.
Soul Hackers 2[]
"The two-headed dog and younger brother of Cerberus who protected the Titan Geryon's red cattle in Greek lore. Despite his skill as a guard, Hercules killed him in one blow while performing one of his twelve great labors."
Orthrus appears both as a Persona of the Hanged Man Arcana and as a weapon for Aigis.
Persona 5[]
"The two-headed pet dog belonging to the giant, Geryon, in Greek myth. He guarded a herd of red oxen, but was killed by Hercules during one of his twelve labors."
When itemized through Electric Chair execution in the Velvet Room, Orthrus yields an Agilao skill card. During a fusion alarm, this is upgraded to a Maragion skill card.
A lone Orthrus is fought early in the exploration of Kaneshiro's Palace, where it is used as a tutorial on how to use Showtime.
In the Path of Da'at, the Shadow has an unrecruitable super variation called the "Light Guardian" who is accompanied by Guard Dog of Paradise.
Persona 5 Strikers[]
"The two-headed pet dog belonging to the giant, Geryon, in Greek myth. He guarded a herd of red oxen, but was killed by Hercules during one of his twelve labors."
—Persona 5 Strikers background
Orthrus appears as a Shadow in the later parts of the Sendai Jail. He is the subject of a request upon reaching the Sapporo Jail, called "Sophia's Armor Shop," in which the party must defeat 5 Orthrus Shadows in order to unlock new armor selections in Sophia's Shop.
Persona 5 Tactica[]
"The two-headed pet dog belonging to the giant, Geryon, in Greek myth. He guarded a herd of red oxen, but was killed by Hercules during one of his twelve labors."
—Persona 5 Tactica background
DemiKids Light & Dark[]
"Fire-breathing demon and brother of Nex. Can burn foes to a crisp."
"The two-headed dog who appears in Greek lore as the younger brother of Cerberus. He protected the titan Geryon's red cattle, but despite his skill as a guard, Hercules killed him in one blow while performing his Twelve Labors."
—Devil Survivor 2 compendium
Shin Megami Tensei: Liberation Dx2[]
"A great two-headed dog in Greek mythology, with a mane and tail of snakes. Orthrus guarded the herds of the monster Geryon, who lived on the island of Erytheia at the edge of the world. However, he was killed by a blow from the club of Heracles, who came to the island as part of his Twelve Labors."