Revealed to be Chiron, a centaur and the activities director at Camp Half-Blood. The greatest...

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

Reveals he is a satyr - half-goat, half-human. He is Percy's protector, assigned to guide him to...

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

A monster with the head of a bull and body of a man. Sent to capture Percy during the storm at...

Son of Poseidon, god of the sea. A demigod with powers over water and earthquakes. One of the 'Big...

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

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

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

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

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

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

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

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

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

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

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

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.

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

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.

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

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.

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

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.

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.

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

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...

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.

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

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.