Due to Zeus's giving birth to Athena, Hera was angry at his actions, and so she birthed Hephaestus (some say parthenogenetically [with the help of a magical herb], others say by Zeus), who Hera hoped was a child so beautiful, so gifted, that it would make Zeus forget his heroic swarm of children from lesser consorts, but nobody celebrated Hephaestus's entering into this world. When the baby was born, she was appalled to see that he was shriveled and ugly, with an irritating bleating wail. She did not wait for Zeus to see him, but snatched the infant up and hurled him from Olympus

Hera spread a rumor that Zeus threw Hephaestus instead of her.

For 24 hours Hephaestus fell, and landed in the sea near the volcanic isle of Lemnos, and was washed up on the shore, where he lay mewing piteously, unable to crawl, and wracked with pain, but unable to die due to his immortality. The Nereid Thetis and the Oceanid Eurynome rescued the broken Hephaestus and hid him from his mother who, ashamed of him, would have continued to harm him.

The god lived with these goddesses in their underwater caves for 9 years. There, he began to craft beautiful jewelry from the underwater coral reefs and metals found underwater. Eventually, Hera saw some of the jewelry and demanded to know the creator. When she learned it was her own son Hephaestus and recognized the beauty he did not possess physically but could create from the physical world, she forgave him for not being what she had hoped for. She asked Zeus to return him to Olympus, but Hephaestus, happy on Lemnos and angry with his mother, would not comply. He gained revenge against Hera for rejecting him by making her a magical golden throne, which, when she sat on it, did not allow her to leave it. The gods begged Hephaestus to return to Olympus to let her go, but he refused, saying "I have no mother."

Therefore, Zeus sent Dionysus to intoxicate him and persuade him to return. Drunk on wine, which he had never previously drank, Hephaestus then rode on a donkey, accompanied by Dionysus, back to Olympus. His mother reclaimed him and he became the Olympian god of fire, forges, volcanoes, metallurgy, stonemasonry, the art of sculpture, technology, blacksmiths, craftsmen, and artisans. Hera presented him with a broken mountain nearby that contained a massive workshop with bellows, anvils, and forges so he could continue to create to the delight of the gods and goddesses. She gave him the Cyclopes to be his helpers. Hephaestus agreed and excused her cruelty to him.

Hephaestus continued to live underground, where he could work as an artisan undisturbed. He grew up to be a huge lump of a man with his shoulders at different heights, a huge, bulging, misshapen head, his leg in a steel brace, and with a wild black beard that sparks fire from time to time. He is the only Olympian to show such extreme physical injuries and the only god to have returned to Olympus after exile. When he is on Olympus, he is clean and elegant, whereas in the forges he wears a jumpsuit smeared with grime and oil. Hephaestus's symbols are the axe, smith's hammer, anvil, fire, and a pair of tongs.

He also built the twelve thrones of Olympus.

In Ancient Greece, Hephaestus was worshiped in the manufacturing and industrial centers, particularly in Athens.

Hephaestus was given Aphrodite's hand in marriage by Zeus in order to prevent conflict over her between the other gods.

Also by Zeus, Hera birthed:

Hebe (hee'bee), "youth", "prime of life", goddess of youth and the cupbearer of the gods and goddesses of Olympus, served their nectar and ambrosia, also drew baths for Ares and helped Hera enter her chariot, became an attendant of Aphrodite and the patron goddess of the young bride, her opposite was Geras

Ares (air'eez), "Leader of Righteous Men", god of war, righteous indignation, courage, battle lust, civil order, male passion, the weapons and preparations for war, the defense and protection of cities, rebellion, policing of banditry, masculinity, anger, fear, and integrity, sacred symbols were the spear, helmet, vulture, dog, eagle owl, and woodpecker

Ilithyia, "she who comes to aid" or "relieve", goddess of childbirth and labor pains

For whatever reason, Zeus disliked Ares the moment he was born and barely tolerated him from then on.

Aphrodite disliked the idea of being married to unsightly Hephaestus, and began an affair with Ares. Ares charged Alectryon, "rooster", a youth, to stand guard outside the door while the god indulged in illicit love with Aphrodite. Alectryon fell asleep, and Helios walked in on the couple and reported the incident to Aphrodite's husband. Hephaestus fashioned an unbreakable chain-link net so small as to be invisible and used this to ensnare the illicit lovers. To make fun of them more, he invited the Olympian gods and goddesses to view and laugh at the naked pair. Poseidon persuaded Hephaestus to free them in return for a guarantee that Ares would pay the adulterer's fine. Once the couple was freed, Ares turned Alectryon into a rooster, which never forgets to announce the arrival of the sun in the morning, and, embarrassed, sped away to his homeland, Thrace.