There is no single original text, like the Christian Bible or the Hindu Vedas, that introduces all Greek myths’ characters and stories. Instead, the earliest Greek myths were part of an oral tradition that began in the Bronze Age, and their plots and themes unfolded gradually in the written literature of the archaic and classical periods of the ancient Mediterranean world.

The poet Homer’s 8th-century BC epics, The Iliad and The Odyssey, for example, tell the story of the Trojan War as a divine conflict as well as a human one. They do not, however, bother to introduce the gods and goddesses who are their main characters, since readers and listeners would already have been familiar with them.

Around 700 BC, the poet Hesiod’s Theogony offered the first written cosmogony, or origin story, of Greek mythology. The Theogony tells the story of the universe’s journey from nothingness (Chaos, a primeval void) into being, and details an elaborate family tree of elements, gods and goddesses who evolved from Chaos and descended from Gaia (Earth), Ouranos (Sky), Pontos (Sea) and Tartaros (the Underworld).

Later Greek writers and artists used and elaborated upon these sources in their own work. For instance, mythological figures and events appear in the 5th-century plays of Aeschylus, Sophocles and Euripides and the lyric poems of Pindar. Writers such as the 2nd-century BC Greek mythographer Apollodorus of Athens and the 1st-century BC Roman historian Gaius Julius Hyginus compiled the ancient myths and legends for contemporary audiences.

At the center of Greek mythology is the pantheon of gods and goddesses who were said to live on Mount Olympus, the highest mountain in Greece. From their lofty perch, they ruled every aspect of human life. Olympian deities looked like men and women (though they could change themselves into animals and other things) and were — as many myths recounted — vulnerable to human foibles and passions..

The twelve main Olympians are:

Other gods and goddesses sometimes included in the roster of Olympians are:

Monsters and “hybrids” (human-animal forms) also feature prominently in the tales: the winged horse Pegasus, the horse-man Centaur, the lion-woman Sphinx and the bird-woman Harpies, the one-eyed giant Cyclops, automatons (metal creatures given life by Hephaestus), manticores and unicorns, Gorgons, pygmies, minotaurs, satyrs and dragons of all sorts. Many of these creatures have become almost as well known as the gods, goddesses and heroes who share their stories.

The characters, stories, themes and lessons of Greek mythology have shaped art and literature for thousands of years. They appear in Renaissance paintings such as Botticelli’s Birth of Venus and Raphael’s Triumph of Galatea and writings like Dante’s Inferno; Romantic poetry and libretti; and scores of more recent novels, plays and movies. Much of the mythology was recorded in D'Aulaires' Book of Greek Myths, published in 1962 and still in print today.