Percy fought the Manticore in "The Titan's Curse." The Manticore is a creature with a lion's body, a human head, and a scorpion's tail.
* Chimera
In "The Sea of Monsters", Percy fought the Chimera, a creature with a lion's head, a goat's body, and a serpent's tail.
* Cyclopes
Percy has fought several Cyclopes throughout his adventures, including Polyphemus, Tyson, and Briares
* Medusa
Percy defeated Medusa, a snake-haired monster, in "The Lightning Thief."
* Echidna
Percy battles Echidna, the mother of monsters, in "The Battle of the Labyrinth"
* Nereid
Percy helps Annabeth fight the Nereid in "The House of Hades"