Guest
Olivea Morton as Nancy Bobofit (season 1), a blunt teacher's pet who relishes tormenting Percy
Hiro Kanagawa as the headmaster of Yancy Academy (season 1). Kanagawa also portrays Kronos' headmaster form in a dream in "We Take a Zebra to Vegas".
Simon Chin as Eddie (season 1), the building superintendent of the apartment building where the Jacksons reside
Manoj Sood as Percy Jackson's second grade principal (season 1)
Jason Gray-Stanford and Garfield Wilson respectively as Maron and Leneus (season 1), two members of the Council of Cloven Elders
Kathleen Duborg as Helena (season 1), a dryad and maternal figure for Grover
Threnody Tsai as Sarah, a wheelchair-using demigod and skilled archer
Jessica Parker Kennedy as Medusa (season 1), a gorgon who lives in solitude and has a past with Percy's father
Sara J. Southey as Tisiphone (season 1), a member of the Furies
Jennifer Shirley (season 1) and Heather Feeney (season 2) as Pythia, the Oracle of Delphi whose mummified remains are in Camp Half-Blood
Suzanne Cryer as Echidna (season 1), the menacing mother of monsters
Joyce Robbins, La Nein Harrison, and Cindy Piper respectively as Atropos, Lachesis, and Clotho (season 1), the three Fates, goddesses of destiny
Timothy Omundson as Hephaestus (season 1), the god of blacksmiths and forges who is strong, compassionate and merciful unlike the other gods
Lin-Manuel Miranda as Hermes, the messenger of the gods and the god of thieves and travelers who is charismatic and boisterous
Ted Dykstra as Augustus (season 1), an older satyr and acquaintance of Grover
Jelena Milinovic as Eudora (season 1), a Nereid who works for Poseidon
Toby Stephens as Poseidon, Percy's father and god of the sea who is stubborn and impulsive
Julian Richings as Procrustes (season 1), a son of Poseidon, Percy's half-brother, and a waterbed salesman who kills people by stretching them to the size of his beds. Richings previously portrayed Charon in the film Percy Jackson & the Olympians: The Lightning Thief (2010).
Jay Duplass as Hades (season 1), the god of the Underworld who is a misunderstood genius and an outcast to his family
Travis Woloshyn as Charon (season 1), the ferryman of the River Styx
Lance Reddick (season 1) and Courtney B. Vance (season 2) as Zeus, the ferocious King of the Olympians whose thunderbolt was stolen in the first season
Kristen Schaal, Margaret Cho, and Sandra Bernhard respectively as Tempest, Wasp, and Anger (season 2), the three Gray Sisters who operate an Olympian taxi service in the Greater New York City area
Marlo Marolle as Mark, a son of Ares
Mark Gibbon, Dan Payne, Daniel Cudmore, Paul Cheng and Kyle Strauts, respectively as Joe Bob, Marrow Sucker, Skull Eater, Brain Biter, and Spine Crusher (season 2), five Laestrygonians that are allied with Kronos. Cudmore previously portrayed a Manticore in scenes that were cut from Percy Jackson: Sea of Monsters (2013).
Gibbon also portrays Chet Jr. (season 2), a Laestrygonian
Cudmore also portrays Skull Crusher (season 2), a Laestrygonian that Luke gets into Camp Half-Blood
Sage Linder as Bronte (season 2), a daughter of Athena
Aiden Howard as Aidan (season 2), a son of Aphrodite and member of Kronos' army
Andra Day as Athena (season 2), Annabeth's mother and the goddess of wisdom
Aleks Paunovic as Polyphemus (season 2), a Cyclops son of Poseidon and guardian of the Golden Fleece who was previously blinded by Odysseus. Paunovic previously portrayed a Cyclops in the film Percy Jackson: Sea of Monsters (2013) alongside Derek Mears.
Rosemarie DeWitt as Circe / C.C. (season 2), a sorceress who Percy and Annabeth encounter in the Sea of Monsters
Jasmine Vega as Hylla Ramírez-Arellano (season 2), a concierge at Circe's spa
Andrew Kavadas as Blackbeard (season 2), a historic pirate captain and son of Ares who was previously turned into a guinea pig by Circe
Dayna Ambrosio as the uncredited voice of the Sirens (season 2), nymphs who draw heroes to their death with alluring music
Viola Abley as Katie Yoon (season 2), a daughter of Apollo
Adam Swain as Ellis Wakefield (season 2), a son of Ares
Series author Rick Riordan makes cameo appearances in the first season as a teacher in the headmasters' office at Yancy Academy and as a statue at Aunty Em's Garden Gnome Emporium.
