Nebiros was first mentioned by Johann Wier in 1583 as Naberius. He is supposedly the most valiant marquis of Hell and has nineteen legions of demons under his command. He makes men cunning in all arts (and sciences, according to most authors), but especially in rhetoric, speaking with a hoarse voice. He also restores lost dignities and honors, although according to Johann Wier, he procures the loss of them.
The 24th spirit of the Goetia, Naberius appears as a three-headed dog or a raven. He has a raucous voice but presents himself as eloquent and amiable. He teaches the art of gracious living. He is depicted as a crow or black crane.
Concerning his name, it is unclear if there is an association with the GreekCerberus. It is said that in 1583, Johann Weyer considers both of them to be the same demon. He claimed:
"Naberius [Naberus], alias Cerberus, is a valiant marquesse, shewing himselfe in the forme of a crowe, when he speaketh with a hoarse voice: he maketh a man amiable and cunning in all arts, and speciallie in rhetorike, he procureth the losse of prelacies and dignities: nineteene legions heare (and obeie) him."
The Grand Grimoire regards Nebiros as the field marshal and inspector general of the armies of Hell. He can be conjured to inflict woes upon anyone, discover the Hand of Glory, teach the mystic and occult qualities of all animals, plants and minerals and supply necromantic advice. One of the three Goetic nobles under his direct authority is Naberius, suggesting that the Grand Grimoires author understood the two spellings to signify distinct demons. The other two subordinates are Glasya-Labolas and Ayperos.
Nebiros appears as a necromancer who, along with a horde of Zombies, invade the protagonist's shelter. After his defeat, the protagonist receives the Fire Talisman from his friend's girlfriend, Hiroko.
"Origin: Africa. The general of Hell. He oversees demons. He has knowledge of ores, plants, and animals, and can forsee the future. He is the most skilled soul controller in all of Hell."
—Shin Megami Tensei A-Mode DDS dictionary
Nebiros appears as the Black Count, a demon who has imprisoned countless souls known as the Bodyconians in an attempt to create a false paradise for his and the Red Baron's adoptive daughter, Alice. Nebiros has imprisoned the girlfriend of the Law Hero as a Bodyconian, and when he attempts to rescue her, his soul is removed, killing him.
Nebiros is one of the four bonus bosses found in the Empyrean Ascent on a New Game Plus. Defeating him bestows the Lucifer Gun (160 AT, hits all, 1 hit; Final Seven skill).
In a similar vein to Maya, Nebiros instantly kills anyone that hits him with a Physical attack. This instant kill effect can be shaken off with Endure. While he does start the battle weak to Gun, at the end of the turn where his weakness is exploited, he will change his weakness and also obscure his elemental affinities. The only constant is that he will always be immune to Expel and Curse, and always drain Ice. For the first half of the battle, Nebiros will preferably use Mabufudyne to assault the party; if any members are known to repel Ice, he will instead spam Calamity Cycle nonstop.
Once he hits half health, he will break out Zero Morality, which inflicts Rage on the party with a high accuracy rate. This can have disastrous consequences, as Rage-afflicted members will use only use Physical attacks and walk right into his instant kill effect. Bring out demons with general ailment immunity to counter this, or keep the Braveheart command skill active to block the incoming ailments.
Like the others, Nebiros will start spamming Doomsday once the battle's gone on for 20 or more turns.
"The general of Hell. He keeps watch over other demons. One of hell's greatest necromancers, he can control souls and corpses."
—Shin Megami Tensei IV Apocalypse compendium
Nebiros appears in Shinjuku in the east entrance main street, Nicho, Kabuki-Cho passage, Kabuki-Cho and the Golden Gai areas. He can teach the Mudoon and Megido skills through his Demon Whisper. Nebiros benefits from learning Darkness and Almighty skills.
Nebiros appears as a boss in [[Kasumidai|Dark Kasumidai during Episode 5. After Tae Asakura and her military contact are drawn into the Dark Realm, Nebiros will reveal himself to Raidou once all of the pages Sadakichi's report are found. While he came to kill the deserter before he can leak any information on the Super Soldier Project, he opts to attack Raidou as well.
Nebiros is also required to unlock the hidden demon, Alice. To do this, he must be in the party to answer the phone at Harumi-Cho after Belial has answered it in Tsukudo-Cho. Then, both must answer the phone at Ginza-Cho, summoning Alice and engaging her in battle. Following her defeat, both will imprison Alice's weakened form in a Staff of Death, asking Raidou to revive her through fusion at the Gouma-Den.
"The general of Hell, he keeps watch over other demons. One of the greatest necromancers in Hell, he can control souls and corpses."
—Persona 3 compendium
Nebiros is a Persona of the Hermit Arcana. His fusion prerequisite requires that the protagonist be level 50 and have the Marionette key item. As the request that grants the Marionette isn't available until special fusions can be performed, Nebiros cannot be fused until after 9/21.
"The general of Hell. He keeps watch over other demons. One of Hell's greatest necromancers, he can control souls and corpses."
—Persona 5 background
Nebiros is the seventh Persona of the Devil Arcana and can be found as a Shadow in Niijima's Palace and in the Depths of Mementos, with the title "Wandering Reviver." He is the first of two Personas to learn the Curse Amp skill and the second of two that learn Evade Bless. Nebiros is the first Persona to learn the Megidolaon skill. When itemized through Electric Chair execution in the Velvet Room, Nebiros yields an Eigaon skill card. Nebiros, together with Belial, is once again one of the Personas needed to summon Alice through fusion.
Nebiros will initially appear as a boss encounter near the end of the dice game area of Niijima's Palace. He will make heavy use of the Brain Jack skill to Brainwash the party, potentially killing the protagonist should those afflicted focus the entirety of their attention on him.
Nebiros can also appear as a low-level Shadow enemy during the first investigation of Maruki's Palace, along with Bugs and Chimera. Aside from its location, nothing about this Shadow differs at all from the version found earlier in the game, and can even be recruited as normal.
Nebiros appears in the Fifth Day at Kudanshita as an optional boss in the event Marquis of Hell. He claims to have appeared on behalf of his master, seeking "the human Bel." He will summon teams led by Badb Cathas, Abbadon and Mothmen, who will heal him when wounded and crowd around him, preventing enemy teams from reaching him. Once defeated, he leaves, acknowledging the party's power and commenting that his master will be pleased. He appears as a member of the Fiend Race in this game.
"The general of Hell. He keeps watch over other demons. One of the Hells greatest necromancers, he can control souls and corpses."
—Devil Survivor 2 compendium
Nebiros appears as a bonus boss on the 3rd Day, but must be unlocked for 30 points.
During the first battle with him, the protagonist needs to escort civilians out of the map, as he enters the field with three demon teams. However, as the party defeats those teams, Nebiros will use Necromancy to constantly revive them at full health (Necromancy resurrects up to all three) whenever his turn comes around.
Furthermore, if Nebiros is defeated while another demon team is present, he can simply reincarnate by taking over that team's body and reappearing at full health, now accompanied by two Pisacas. Thus, the party either has to mobilize all 4 teams to efficiently defeat him, or make use of the Kishins' Double Up/Matchless Racial Skills.
Defeating Nebiros causes him to retreat, earning the player the Nebiros Repeller title and unlocking the fight with Belial on the 5th Day.
During the fight with Alice, Nebiros appears alongside Belial. Like the previous fight, Nebiros will revive defeated demon teams and reincarnate himself if defeated while any loose team is present. He also has his Ice and Electricity affinities improved, along with being buffed to Level 91.
In spite of Nebiros' status in the demonic hierarchy and his mid-major role as a secret boss, he is not a unique demon, allowing the party to have multiple Nebiros demons on their team.