A host of legendary creatures, animals, and mythic humanoids occur in ancient Greek mythology.
They were the offspring of Gaia (Earth), born from the blood that fell when Uranus (Sky) was castrated by their Titan son Cronus, who fought the Gigantomachy, their war with the Olympian gods for supremacy of the cosmos.
Among the Gigantes whose names survive in literary or epigraphic sources are: The dragons of Greek mythology were serpentine monsters.
Drakons ("δράκους" in Greek, "dracones" in Latin) were giant serpents, sometimes possessing multiple heads or able to breathe fire (or even both), but most just spit deadly poison.
In addition to the famous deities, the ancient Greeks also worshiped a number of deified human beings.