Hera

The wife and sister of Zeus; the goddess of marriage, often depicted as regal, often enthroned, topped with the "polos," a tall cylindrical crown worn by some major goddesses. She was pictured as carrying in her hands the pomegranate, a symbol of fertile blood and death. Her union with Zeus produced four children, namely: Ares (god of war), Hebe (goddess of youth), Eileithyia (goddess of childbirth) and Eris (goddess of discord). Most of all, she was best known for her jealous and revengeful spirit, not only toward the mortals who opposed her like Paris (who earned her ire by picking Aphrodite as the most beautiful goddess) and Pelias (who desecrated her temple) but especially toward her husband's mistresses and their children by him.
Danae

The daughter of King Acrisius of Argos and Eurydice. Frustrated by his lack of male heirs, Acrisius sought an oracle and was told that he would be killed by his daughter's son. Intending to keep her daughter childless, he locked her up in a bronze tower or cave, where Zeus came and had intercourse with her in the form of a golden shower, impregnating her. Not long after was born the hero Perseus, who would become the slayer of Medusa and the rescuer of Andromeda; and who would also unwittingly fulfill the oracle when he accidentally struck his father with a discus in an athletic contest.
Europa

A Phoenician princess. Zeus, very much enamored with Europa, transformed himself into a tame white bull and was able to blend in quite well with her father's herds. While Europa was busy picking flowers, she noticed the bull and stroke him, eventually climbing onto his back. Zeus, not one to miss a golden opportunity, ran toward the sea and swam to the island of Crete, where he exposed his real identity, made her the first queen of the island and lavished her with many gifts. Three sons were born to them: Minos, Rhadamanthus and Sarpedon, all of whom became judges of the dead in Hades upon their deaths.
Alcmene

The daughter of Mycenaean king Electryon, and wife of Amphitryon. During her husband's absence, she was visited by Zeus, who assumed the likeness of her husband and slept with her for three consecutive nights. Shortly thereafter, she slept with her husband upon his return; and would eventually give birth to twins: Iphicles by her husband; and Heracles (Roman Hercules) by Zeus, who was best known for his many adventures featuring extraordinary feats of strength and courage.
Aegina

The daughter of the river-god Asopus and the nymph Metope. She was abducted by Zeus who took the form of an eagle; and was carried to an uninhabited island near Attica called Oenone; the island hereafter became known by her name. A son was born to her named Aeacus, who became the king of the island after Zeus created inhabitants out of the ants of the islands known as the Myrmidons.
Callisto

The daughter of Lycaon, king of Arcadia. As with all devotees of Artemis, she vowed to remain a virgin, but she would lose her virginity to the insatiable Zeus, who seduced her into his embrace and ravished her disguised as Artemis. She was subsequently turned into a bear by a very jealous Hera who was so enraged upon discovery of her pregnancy. Her son, Arcas, almost killed her in a hunting expedition, but Zeus averted the tragedy and placed them both in the sky as Ursa Major and Ursa Minor.
Io

The daughter of the river god Inachus. She was taken one day by the ever-lustful Zeus and continued on in their relationship until Hera almost caught them in the act. However, Hera was not deceived even when Zeus changed himself into a white cloud and Io into a white heifer to avoid detection. She demanded the heifer as a gift, and placed her under the charge of the ever-awake hundred-eyed monster Argus. To free Io, Zeus had Argus killed by Hermes who lulled all its eyes to sleep with boring stories. But then, Hera forced Io to roam about the earth without ceasing, and sent a gadfly to harass her into insanity. In due course, she ultimately reached Egypt, where she was changed back to human form by Zeus; and gave birth to Epaphus, who would become one of the ancestors of the greatest of all heroes, Heracles.
Leda

The Spartan queen and wife of Tyndareus. She was deeply desired by Zeus, who fell into her arms in the guise of a swan seeking refuge from a pursuing eagle and then raped her. Their consummation came on the very same night she also laid with her mortal husband. As a result, two eggs were hatched, each containing a set of twins: Pollux (Polydeuces) and Castor (collectively known as the Dioscuri); and Clytemnestra and Helen "of Troy." Thus, half of the twins were wholly mortal while the other, half-immortal.