Hercules (who was also known as Heracles), was the son of Zeus and Alcmene, the wife of Amphitryon. As a father, Zeus had great hopes for his offspring. On the day of his birth, he announced to all the gods the arrival of a child to his kingdom who would become king. Hera, who was the guardian of married women, delayed the arrival of Hercules. Eurystheus, the cousin of Hercules, who was a "spineless creature", came into the world before Hercules. Zeus had to live up to his promise and made Eurystheus king. As a result of this, Hercules could only be a champion in his service to his family and the world.
Hercules demonstrated his strength right from birth. He choked the serpents that had been sent to him by the jealous Hera. When he was born, he was first named Alcide ("the strong") but was renamed "Heracles" ("the glory of Hera") after overcoming the tests that were imposed on him by Hera.
Hercules was educated by Linus, the musician. He learned literature and music but was found to be a mischievous student. When Linus wanted to beat him one day, Hercules grabbed a stool and hit Linus with it, killing him. At his trial, Hercules was acquitted on the grounds that he was only defending himself. Amphitryon feared his adopted son (most likely due to his strength) and sent him to a Scythian cattleman, Teutarus, who taught Hercules archery.
At the age of eighteen, Hercules spent fifty days trying to kill the lion of Cithaeron. Each night he returned to the palace of King Thespius. Because King Thespius wanted to have Hercules father his grand-children, he put one of his fifty daughters in Hercules' bed each night. Thus, Hercules had fifty sons, the Thespeiades, who would eventually colonize Sicily.
Hercules married Megara, the daughter of the Theban king. However, this marriage was not successful. Hera, who was still jealous of Hercules, made Hercules go mad and made him kill his children and threaten Amphitryon, who would have died because of Hercules if Athena hadn't stopped him. To repent from his crime, he decided to leave his wife, Megara, and put himself at the service of Eurystheus, his cousin who was now king.
Eurystheus sent Hercules on a mission over his twelve years of servitude, a mission with twelve labours. On his mission of twelve labours, he strangled the Nemean lion and made himself armour from the hide. Secondly, he cut off the many heads of the Lernaean Hydra and brought back the enormous Erymanthian Boar alive. With his arrows, he shot down the many birds of the Stymphalian Marsh who raided the crops and killed men. As well, he cleaned the stables of Augeias by diverting the courses of two big rivers, the Alpheus and the Peneius. He completed this task in just one day. Furthermore, he brought back the angry Cretan Bull (alive for that matter) who breathed fire through his nostrils. He killed Diomedes, who gave his horses human flesh to eat. He also seized the girdle given by Ares to Hippolyta. Using the sun's golden cup, he brought Geryon's cattle back to Greece from the Far East, fighting along the way with enemies who included Neleus, who was the king of Pylus. Hercules retrieved the golden apples from the Garden of the Hesperides, challenging the giant, Antaeus, the Pygmies and the dragon, Ladon, and freeing Prometheus on the way. Lastly, from Hades, he brought Cerberus, the dog who defended the gates of Hades.
When he returned back to Eurystheus, he brought back the results of each labour to Eurystheus. Because Eurystheus was afraid of Hercules, Eurystheus shut himself within a bronze jar to protect himself.
It is impossible to list all the feats that Hercules achieved. Hercules travelled everywhere, including the depths of hell. He stood up to the forces of a different kind and succeeded in injuring Hades and Hera with his arrows. Because of his feats, he was considered a superhuman, conceivably already a god.
Hercules won the hand of Deianeira and lived with her in Calydon. Soon, after being chased by bad luck and Hera's vengefulness, he accidentally killed one of his father-in-law's pages. As a result of this incident, he had to leave with his wife and son and when they crossed the River Evenus. Nessus, the boatman, tried to rape Deianeira. Before Nessus was killed by Hercules, he had enough time to tell her that his blood was a love potion which would bring back her husband's affection should she ever lose his affection.
After, Hercules went mad and went to ask Pythia, priestess of Apollo, of her opinion. She said that to free himself of this evil, he must sell himself as a slave to someone. Omphale, the Queen of Lydia, bought him and he was in her service for three years. This long separation between Hercules and Deianeira led him to court Iole, who was the daughter of Eurytus. However, when Deianeira was informed of this, she sent a new piece of clothing to Hercules which she had soaked in Nessus' blood.
Hercules, who suspected nothing, put on the tunic and was seized by incredible pain. He tried to tear the piece of clothing off but it stuck to his skin; the love potion turned out to be poison. Hercules built a pyre and asked his companions to ignite it.
When the flames started to leap into the air, there was a strike of thunder, and Hercules was taken up to heaven; he had just been immortalized. On Olympus, he married Hebe (the goddess of eternal youth) and settled his differences with Hera.