Which fatal illness shall I use to kill the great Apolloooo? Anthrax? Perhaps eboooola…

–Nosoi, in The Hidden Oracle

The Nosoi (Singluar "Nosos") are the spirits of illness, plague, and disease. They were one of the many evils locked inside Pandora's Pithos. They are sometimes likened to the Keres. Their Roman equivalent are the Morbi.


The Trials of Apollo

The Hidden Oracle

Several Nosoi were following Meg McCaffrey and Apollo, as they were on their way to see the demigod Percy Jackson. Meg described them as "shiny blobs".

On their way to Camp Half-Blood, Apollo, Meg, and Percy were attacked by a group of three Nosoi. One of them manages to infect Apollo. They are weakened by Meg, who used her demigod powers, and later finished off by her friendly KarposPeaches.


The Nosoi, in their basic form, were described as vaguely humanoid apparitions. Their bodies are made of glimmering smoke, which renders them invulnerable to any weaponry, even ones made from blessed metals such as Riptide. They can change their form into semi-corporeal; resembling ghoulish corpses with yellow eyes, dressed in destroyed clothes, and covered in festering wounds. Any sort of attack will simply pass through them.


The Nosoi are embodiment of fatal diseases. When they are in their smoke form, they can infect people by making them inhale the vapors of their bodies.


  • The Nosoi were responsible for the Black Death in the 14th century.
  • Nosoi are often depicted as ravens wearing plagues masks.
Enemy Spirits Arai | Aurae | Eidolons | Karpoi | Keres | Nosoi | Makhai | Mania | Venti
Friendly Spirits Nereids | Dryads | Lares | Naiads | Nebulae
Neutral Spirits Maenads
The Trials of Apollo
Core Series: The Hidden Oracle | The Dark Prophecy | The Burning Maze | The Tyrant's Tomb
Main Characters: Apollo/Lester Papadopolous | Meg McCaffrey | Peaches | Leo Valdez | Calypso | Grover Underwood | Piper McLean | Reyna Ramírez-Arellano
Minor Characters: Percy Jackson | Sally Jackson | Nico di Angelo | Will Solace | Chiron | Rachel Elizabeth Dare | Thalia Grace | Mrs. O'Leary | Festus | Cade | Mikey | Kayla Knowles | Austin Lake | Harley | Connor Stoll | Miranda Gardiner | Cecil Markowitz | Ellis Wakefield | Sherman Yang | Damien White | Malcolm Pace | Paolo Montes | Germani | Agamethus | Hemithea | Josephine | Georgina | Lityerses | Olujime | Hunter Kowalski | Sssssarah | Trophonius | Prickly Pear | Aloe Vera | Joshua | Gleeson Hedge | Mellie | Chuck Hedge | Naevius Sutorius Macro | Incitatus | Crest | Tristan McLean | Medea | Jason Grace | Herophile | Lavinia
Olympian Gods: Zeus | Hera | Poseidon | Demeter | Ares | Athena | Artemis | Hephaestus | Aphrodite | Hermes | Dionysus | Hades
Minor Gods: Nero | Iris | Britomartis | Commodus | Styx | Caligula
Titans: Rhea | Leto | Mnemosyne | Helios
Monsters and Magical Creatures: Python | Nosoi | Karpoi | Palikos | Myrmeke | Colossus Neronis | Blemmyae | Gryphon | Carthaginian Serpent | Scythian Dracaena | Cynocephali | Centaur | Cyclops | Yale | Satyr/Faun | Dryad | Strix | Dragon | Pandai | Eurynomoi
Related Content: Rick Riordan | Percy Jackson and the Olympians | The Heroes of Olympus | Demigods & Magicians | Camp Half-Blood Confidential | Percy Jackson Demigod Collection
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