Polyphemus the gigantic one-eyed son of Poseidon and Thoosa; one of the Cyclopes

Poseidon the Greek god of the sea; son of the Titans Kronos and Rhea, and brother of Zeus and Hades praetor an elected Roman magistrate and commander of the army

Primordial Chaos the first thing ever to exist; a void from which the first gods were produced Prometheus the Titan who created humans and gifted them with fire stolen from Mount Olympus Pythia the name given to every Oracle of Delphi

Python a monstrous serpent that Gaea appointed to guard the Oracle at Delphi

Rhea Silvia the queen of the Titans, mother of Zeus

Riptide the name of Percy Jackson’s sword; Anaklusmos in Greek

River Styx the river that forms the boundary between earth and the Underworld

Saturnalia an ancient Roman festival celebrating Saturn (Kronos)

satyr a Greek forest god, part goat and part man

shadow-travel a form of transportation that allows creatures of the Underworld and children of Hades to use shadows to leap to any desired place on earth or in the Underworld, although it makes the user extremely fatigued Sibyl a prophetess

Sibylline Books a collection of prophecies in rhyme written in Greek; Tarquinius Superbus, a king of Rome, bought them from a prophetess and consulted them in times of great danger siccae a short curved sword used for battle in ancient Rome

Sparta a city-state in ancient Greece with military dominance

Stygian iron a magical metal, forged in the River Styx, capable of absorbing the very essence of monsters and injuring mortals, gods, Titans, and giants; has a significant effect on ghosts and creatures from the Underworld Talos a giant mechanical man made of bronze and used on Crete to guard its shoreline from invaders Tantalus According to legend, this king was such a good friend of the gods that he was allowed to dine at their table—until he spilled their secrets on earth; he was sent to the Underworld, where his curse was to be stuck in a pool of water under a fruit tree, but never be able to drink or eat Tartarus husband of Gaea; spirit of the abyss; father of the giants; a region of the Underworld Theodosius the last to rule over the united Roman Empire; known for closing all ancient temples across the empire Thracian of Thrace, a region centered on the modern borders of Bulgaria, Greece, and Turkey Titan War the epic ten-year battle between the Titans and the Olympians that resulted in the Olympians taking the throne Titans a race of powerful Greek deities, descendants of Gaea and Ouranos, that ruled during the Golden Age and were overthrown by a race of younger gods, the Olympians trireme a Greek warship, having three tiers of oars on each side

triumvirate a political alliance formed by three parties

Trojan War According to legend, the Trojan War was waged against the city of Troy by the Achaeans (Greeks) after Paris of Troy took Helen from her husband, Menelaus, king of Sparta Troy a Roman city situated in modern-day Turkey; site of the Trojan War

Tyche the Greek goddess of good fortune; daughter of Hermes and Aphrodite

Typhon the most terrifying Greek monster; father of many famous monsters, including Cerberus, the vicious multi-headed dog tasked with guarding the entrance to the Underworld Underworld the kingdom of the dead, where souls go for eternity; ruled by Hades

Zephyros the Greek god of the West Wind

Zeus the Greek god of the sky and the king of the gods

RICK RIORDAN, dubbed “storyteller of the gods” by Publishers Weekly, is the author of four New York Times #1 best-selling series: Percy Jackson and the Olympians and The Heroes of Olympus, based on Greek and Roman mythology; the Kane Chronicles, based on Egyptian mythology; and Magnus Chase and the Gods of Asgard, based on Norse mythology. His two Greek myth collections, Percy Jackson’s Greek Gods and Percy Jackson’s Greek Heroes, illustrated by John Rocco, were New York Times #1 best sellers as well. Rick lives in Boston, Massachusetts, with his wife and two sons.