Joins Percy's quest to find Zeus's master bolt. Her wisdom and strategy are essential to the...

Railroad employee at Denver station who assists passengers with connections and schedules.

Joins Percy's quest to find Zeus's master bolt. His wilderness survival skills and ability to sense...

Chosen for a quest to retrieve Zeus's master bolt. Must travel to the Underworld to find it.

Railroad employee who manages passenger boarding and tickets on the westbound train.

Family traveling by train who shares the car with Percy, Annabeth, and Grover during their journey...

Reveals her true form as a winged demon and attacks Percy with her whip and talons.

An unclaimed camper in the overcrowded Hermes cabin, skilled at minor theft and pranks.

The food of the gods that heals demigods when they're injured. Tastes like favorite foods to each...

City official who handles the reward for finding and returning the lost poodle Gladiola.

Goddess of love and beauty. Has children at Camp Half-Blood known for their charm and beauty.

God of the sun, music, poetry, and prophecy. Has a cabin at Camp Half-Blood with skilled archers...

Tourist visiting the Gateway Arch who witnesses strange events but dismisses them due to the Mist.

Instructor who teaches archery skills to campers, working closely with Apollo cabin members.

The many-eyed security chief of Camp Half-Blood who drives the camp van and watches over everything.

Staff member responsible for maintaining and distributing weapons to campers for training.

Goddess of the hunt and moon. Twin sister to Apollo. Rarely has children but is mentioned as patron...

Camp counselor who runs creative activities and helps campers make various art projects.

Had a rivalry with Poseidon that resulted in Medusa's curse. Her wisdom cabin children inherit her...

A son of Apollo with musical talents who plays various instruments around camp.

Luke's sword, a gift from his father Hermes. Made of both celestial bronze and steel.

A daughter of Demeter who specializes in growing medicinal herbs for the camp infirmary.

A black pegasus at Camp Half-Blood who forms a connection with Percy due to their shared Poseidon...

A daughter of Athena who excels at puzzles and architectural planning.

The driver of the school bus that transports Yancy Academy students to and from field trips.

A mortal passenger on the Greyhound bus who is unaware of the supernatural quest happening nearby.

Food service worker at Yancy Academy who serves lunch to the students.

Magical boundaries that protect Camp Half-Blood from monster attacks, powered by Thalia's tree.

The head cook at Camp Half-Blood who prepares meals for all the campers and staff.

Medical staff member who helps treat camper injuries alongside Apollo children.

The camp store run by nymphs where campers can buy supplies and snacks.

Water sports instructor who teaches canoeing and swimming at the camp lake.

One of the head counselors of Dionysus cabin. Twin brother to Pollux, both sons of Mr. D.

Magical metal that can harm monsters and gods but passes harmlessly through mortals.

Elder centaurs who advise Chiron and help oversee the training of heroes throughout history.

Shows Percy some of his mechanical inventions and helps repair weapons damaged in capture the flag.

A monster with the head of a lion, body of a goat, and tail of a serpent. Breathes fire and poisons...

Has trained heroes for over three thousand years including Hercules and Achilles. Immortal centaur...

A son of Hermes in Cabin Eleven. One of the many unclaimed campers living in the overcrowded Hermes...

Leads the red team in Capture the Flag. Her electric spear is broken when Percy defeats her in...

Camp staff who operates the lava-filled climbing wall and ensures camper safety during practice.

Twin brother of Travis and son of Hermes. Equally mischievous and skilled at pranks.

One-eyed giants who work as blacksmiths for the gods, crafting divine weapons and tools.

Goddess of agriculture and the harvest. Her children have abilities with plants and growing things.

Kitchen staff at the roadside diner who prepares food for travelers.

Server at a roadside diner who takes the quest group's order and serves their meal.

Adult supervisor who manages the dormitory at Yancy Academy and enforces curfew rules.

Snake-like monsters with the upper bodies of women who serve as scouts and warriors.

A daughter of Aphrodite known for her beauty and vanity. Often seen applying makeup and gossiping.

The Mother of Monsters who appears as a woman with a Chihuahua. Attacks Percy at the Gateway Arch...

One of Gabe's poker friends who comes over to play cards and drink beer.

An older woman on the bus who knits and talks to other passengers during the long journey.

A son of Ares known for his aggressive fighting style and competitive nature.

The psychic connection between Percy and Grover that allows them to sense each other's emotions and...

Monsters that disguise themselves as beautiful women to lure and feed on travelers.

Percy's English teacher at Yancy Academy who struggles with Percy's dyslexia and reading...

His terrible smell actually helps mask Percy's demigod scent from monsters, which is why Sally...

Worker at a highway gas station who helps travelers with fuel and directions.

Security officer at the Gateway Arch who monitors visitors and ensures safety protocols.

Guide who explains the history and construction of the Gateway Arch to visiting tourists.

A pink poodle that Percy, Annabeth, and Grover find and return for the reward money. Can talk to...

A legendary magical item mentioned as having great healing powers. Part of Luke's failed quest.

The bus driver who transports passengers westward, including Percy, Annabeth, and Grover on their...

Physical education teacher at Yancy Academy who runs sports activities and fitness classes.

Student hall monitor at Yancy Academy who reports troublemakers to the administration.

A young son of Hephaestus who shows promise in mechanical work despite his age.

Large demonic dogs from the Underworld that hunt demigods on behalf of their master Hades.

God of fire, metalworking, and crafts. His children are skilled builders and mechanics.

Distant father who rarely visits his children. His neglect contributes to Luke's resentment of the...

Nymphs who guard the Garden of the Hesperides and its golden apples, part of Luke's failed quest.

Goddess of the hearth and home, mentioned as maintaining the camp's central fire.

History instructor at Yancy Academy who teaches about ancient civilizations and cultures.

Goddess of the rainbow who runs Iris-messaging service. Allows communication through rainbow mist.

A son of Hephaestus who works alongside Beckendorf in the camp forge, crafting weapons and tools.

A classmate of Percy at Yancy Academy who attends the same classes and field trips.

The school janitor at Yancy Academy who cleans up after student incidents and mishaps.

An unclaimed camper hoping her godly parent will recognize her and give her a proper cabin.

Head counselor of the Demeter cabin. Skilled with plants and growing things like her divine mother.

A daughter of Apollo known for her excellent archery skills and musical abilities.

The dragon that guards the golden apples in the Garden of the Hesperides and gave Luke his scar.

Giant cannibals who disguise themselves among mortals and hunt demigods for food.

Leads the Apollo cabin archers during capture the flag, providing covering fire for the other...

The school librarian at Yancy Academy who maintains the books and helps with research.

Went on a quest to retrieve a golden apple from the Garden of the Hesperides but failed. Bears a...

Participates in camp activities and helps with strategic planning like other children of Athena.

A son of Athena known for his strategic thinking and research skills in the camp library.

Additional math support teacher who helps Percy with his algebra struggles at Yancy Academy.

A bully at Yancy Academy who picks on younger students and enjoys tormenting Percy.

A monster with snakes for hair who turns people to stone. Disguises herself as 'Auntie Em' running...

Another student at Yancy Academy who witnesses Percy's various school incidents.

Defeated by Percy who rips off its horn and uses it to kill the creature. Percy's first monster...

A daughter of Demeter skilled with plants and agriculture. Helps maintain the camp gardens.

River boat captain who operates vessels on the Mississippi River near the Gateway Arch.

A son of Aphrodite who enjoys fashion and has an eye for style like his divine mother.

Tourist at Montauk Beach who enjoys the seaside location where Percy and Sally have their special...

Beach safety officer who monitors swimmers and beach activities at Montauk Beach.

Revealed to be Dionysus, god of wine. Punished by Zeus to serve as camp director for 100 years....

The headmaster of Yancy Academy. Stern administrator who deals with Percy's disciplinary issues.

Part of the Mist's illusion that makes mortals forget the supernatural events that occurred.

Security guard at the Metropolitan Museum who patrols the exhibits and ensures visitor safety.

The guide at the Metropolitan Museum who leads Percy's class through the Greek and Roman exhibits.

Water spirits that inhabit the lakes and streams around Camp Half-Blood and communicate with Percy.

Gets pushed into the fountain by Percy using his powers, though no one believes it was him.

The drink of the gods that heals demigods. Too much can burn up a half-blood from the inside.

Gives Percy three pearls from his father that will transport him and two others back to the sea in...

A daughter of Hephaestus skilled in metalworking and mechanical devices. Works in the forge.

The mummified Oracle at Camp Half-Blood that gives prophecies. Speaks in riddles about Percy's...

Winged horses at Camp Half-Blood that are children of Poseidon and can fly campers around.

An unclaimed camper living in Hermes cabin, waiting for his godly parent to claim him.

Twin brother of Castor and co-head counselor of Dionysus cabin. Son of Mr. D.

Wealthy family member who owns Gladiola the pink poodle and offers a reward for her return.

Percy's father, god of the sea, earthquakes, and horses. One of the 'Big Three' gods who swore not...

Assistant principal at Yancy Academy who handles student discipline and behavior issues.

A ballpoint pen that transforms into a celestial bronze sword when uncapped. Given to Percy by...

Had a relationship with Poseidon before Percy was born. Married the horrible Gabe because his smell...

A student at Yancy Academy who shares classes with Percy and goes on school trips.

The nurse at Yancy Academy who treats student injuries and handles medical issues.

Percy's science teacher at Yancy Academy who teaches chemistry and biology courses.

Participates in capture the flag with the red team, showing typical Ares cabin aggression.

Head counselor of Aphrodite cabin. Beautiful and charming like her mother, with extensive knowledge...

Camp staff member who maintains the pegasus stables and cares for winged horses.

Teacher who supervises study hall periods and maintains quiet study environments.

Her tree contains powerful magic that protects Camp Half-Blood from monsters. Her sacrifice saved...

Three ancient sisters who punish those who break sacred laws. Alecto is one of them hunting Percy.

Causes mortals to have false memories about events, like remembering Mrs. Kerr instead of Mrs....

Percy's roommate at Yancy Academy who shares the dormitory room and witnesses Percy's odd behavior.

Helps initiate Percy into camp life and teaches him about the various camp traditions and rules.

Long-haul trucker who stops at the same truck stop and offers travel advice.

Store clerk at a highway truck stop where the quest group stops for supplies.

A son of Apollo skilled in healing and archery. Often helps in the camp infirmary.

Nature spirits that live in trees around Camp Half-Blood. Some work in the camp store.

King of the gods and god of the sky. His master bolt has been stolen, threatening war. Suspects...