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 stepfather who is lazy, rude, and smells terrible. Plays poker with his friends and treats...

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

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.

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

Shows unusual powers - vaporizes his pre-algebra teacher Mrs. Dodds who turns out to be a Fury. Can...

Percy's mother who can see through the Mist. Beautiful woman with kind eyes who smells like...

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.

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.

Percy's Latin teacher at Yancy Academy. Uses a wheelchair and takes a special interest in Percy's...

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.

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

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.