Perseus (Περσεύς) was son of Zeus and Danaë (Danae), daughter of Acrisius (Acrisios or Ἀκρίσιοσ), king of Argos, and Eurydice. Perseus was also a descendant of the heroine Io, who was living in exile in Egypt. A descendant of Io, named Danaüs returned to Io's homeland, and became king of Argos.

Acrisius was himself a great-grandson of Danaüs. Acrisius was the twin brother of Proëtus, his main rival over the throne of Argos. Proëtus to settle being king of the neighbouring city, Tiryns.

When Acrisius heard oracle from Delphi, he was told instead that a child from his daughter is destined to kill him. Acrisius fearing his destiny imprisoned his daughter in a tower. But the god Zeus, appeared in the form of shower of gold, had sex with Danaë (Δανάη).

(Apollodorus indicated another version of Perseus' conception. Apollodorus wrote that the real father was Proëtus, brother and rival of Acrisius. Proëtus had seduced his niece, so that Danaë became pregnant. Zeus as a shower of gold was of course the most popular version.)

Having found that Danaë had given birth to a son, Perseus, Acrisius locked both mother and child in a chest and threw them into the sea. Zeus asked his brother, Poseidon, to guide the chest to the island of Seriphus, where the fisherman Dictys found them. Dictys was a son of Magnes and a naiad nymph, brother of Polydectes. Magnes being a son of Aeolus, would make Dictys and Polydectes Aeolids.

When Perseus grew into a strong young man, Polydectes, who was Dictys' brother, was the king of Seriphus, fell in love with Danaë. Polydectes wanted to marry her, but did not want or like her son, Perseus.

Polydectes invited Perseus to a celebration. Polydectes falsely announcing his plan to marry a daughter of Oenomaüs, Hippodameia, and each guest had given a gift to the king. Perseus, who brought no gift, rashly promised to the king that he would give any gift that the king wished.

Polydectes couldn't believe his good fortune of getting rid of the youth, asked for the head of the Gorgon Medusa, knowing that the youth could never possibly return home alive. Perseus readily agreed. Only later, did Perseus realising the depth of his promise, founded that his task was seemingly all but impossible.

There were three Gorgons, and only Medusa (Μέδοισα) was mortal, since she was originally maiden, whom Poseidon had lain with, in the goddess Athena's shrine. Incurring the goddess' enmity for this sacrilege, Athena turned unfortunate girl into a winged monster with a head full of snakes instead of hair, where a single glance of her hideous face was so deadly, she would turned any creature instantly into stone.

Even if Perseus managed to kill Medusa, the other two Gorgons would fall upon him before he could escape.

But the goddess Athena appeared and came to her mortal half-brother's aid and told him that he needed to fetch some vital equipment, if he was to succeed in his quest. Athena directed him to a cave the Libya, where two hags (some say three), known as the Graeae, who shared a single eye and a single tooth. Perseus had to snatch the eye as they passed them, forcing the hags to tell where to find weapons to defeat the Gorgons. The Graeae told him of the whereabouts of the nymphs.

The nymphs readily aided Perseus in his quest, giving him a magic bag (kibisis), a pair of winged sandals and the cap of invisibility.

Athena warned him, to never look directly at the Gorgon's face, but rather look at Medusa's reflection on the bronze shield, which she gave him.

The god Hermes gave him either a sickle of adamant. Note that this adamantine sickle was probably the same one that the Titan Cronus had used against his father Uranus, and that Zeus had to fight against the monster Typhon; see the Creation.

Now fully armed, Perseus flew off to find Medusa.

Perseus found their lair, surrounded by people and animal that had turned into stone. Invisible, Perseus watches them through the reflection of the shield and waited until the Gorgons were asleep.

Avoiding the two immortal Gorgons, Perseus crept up to Medusa and severed her head from her body. Snatching the head and placing it in the magic bag, Perseus quickly flew away, as the other two Gorgons awoken, but could not see their attacker, therefore not being able pursue him.

Some of the blood from Medusa's head, leaked out of the bag. A drop of Medusa's blood fell into the sea, Pegasus (Πήγασος), the winged horse was born. Another drop of blood had fallen on the ground in Libya, so a giant sprang out of the earth, known as Chrysaor (Χρυάωρ).

Flying past the city of Joppa, in Syria, Perseus found a beautiful maiden chained to a rock at the beach. She was Andromeda (Ἀνδρομέδη), daughter of the king Cepheus. His vain wife Cassiopeia boasted that she was more beautiful than the Nereïds (Nereids). In anger, the Nereïds requested to Poseidon to send a sea monster, called Cetus, to destroy the city. Only a sacrifice of the king's daughter would spare the town.

Hearing their story from Andromeda's parents, Perseus bargained with the king for the girl's hand in marriage. Some accounts have it that Perseus fought the monster and killed Cetus with his sickle. Others say that he turned the creature into stone by displaying the head of Medusa to the monster.

Cepheus held a banquet to honour the young hero, but Andromeda was promised in marriage to Cepheus' brother, Phineus, who had come to claim her. Perseus told Phineus that he had saved Andromeda's life and that the king had agreed to reward Perseus should he defeat the monster, so he had the strongest claim. Perseus, who made some friends in court, supported Perseus' claim, but they were heavily outnumbered. At this point, Cepheus and Cassiopeia had left the court to avoid confrontation and taking side.

Fighting broke out between two factions over who had the best claim to marry Andromeda. After Perseus had killed many of Phineus' followers, Perseus told his new friends to shield their eyes, when he pulled Medusa's head from his bag, turning his enemies into stone.

Perseus and Andromeda were shortly married after the battle, and then had a son, named Perses. Perseus decided to return home in Seriphus, but left his son behind so that Perses would inherit Cepheus' throne.

With his new wife, Perseus travelled back to Seriphus and founded that his mother and Dictys had taken refuge in a temple. During his absence, Polydectes had pursued his mother, Danaë (Danae), trying to force himself upon her. Danaë refused to the safety of the sanctuary. Perseus was furious at Polydectes' action since his absence.

Leaving Andromeda with his mother and went out alone to seek and confront Polydectes in the palace.

At the banquet, the king and nobles did not believe that Perseus was successful in his quest and returned with head of Medusa. Polydectes knew that Perseus would either return home empty-handed or that he would die in the quest. So Polydectes and his court laughed at Perseus' failure.

Their laughter died in their lips, when Perseus took out the head and held up the severed head of Medusa. All the onlookers in the king's court, paled at the hideous sight, their skin and flesh hardening as they gazed at the deadly face of the Gorgon. In a matter of moment, Polydectes and everyone within the banquet hall, except Perseus, had turned into stone.

Having achieved the impossible task, Perseus decided it was too dangerous to keep Medusa's head, because it would turn his friends as well as his enemies into stone, because the gaze of the Gorgon doesn't make any distinction between the two. Perseus gave the head of Medusa to Athena, who placed the head in the centre of her aegis.

The weapons, flying sandals and the helm of invisibility he had borrowed from the gods, he now returned to Hermes and Athena.

Perseus with his wife and mother had only stayed on Seriphus for a little while, before they decided to sail away. Their destination was to return to Argos, leaving Dictys to become the king of the island, since the good fisherman was Polydectes' brother.

There are a couple different accounts about Acrisius' death, but the usual story is this. Acrisius (Acrisios) having heard of his grandson's heroic adventure and his decision to come to Argos caused the old king to flee. But Perseus did not want to harm his grandfather, nor did he want Acrisius' throne. Perseus followed Acrisius to Larisa in Thessaly.

Teutamides, the king of Larisa, was holding funeral games for his father. Perseus wanted to demonstrate his prowess in athletics, took part in discus throwing. The wind blew the discus astray, accidentally killing Acrisius, thereby fulfilling the oracle that his grandson would eventually kill him. According to Hyginus, the discus struck Acrisius in the head, while Apollodorus wrote that it had struck the king on the foot; Hyginus' was the preferred version.

Though Perseus inherited the throne of Argos, by right of birth, he was ashamed of himself for accidental killing of his grandfather. Perseus decided to trade his kingdom with either his great uncle Proëtus (Acrisius's brother), or with Proëtus' son Megapenthes, for the city of Tiryns. So Perseus became the king of Tiryns.

During his reign, Perseus founded a new city, which he called Mycenae. Mycenae became even more powerful than Tiryns.

Andromeda bore him a daughter, Gorgophone and five more sons: Electryon, Alcaeüs (Alcaeus), Sthenelus, Mestor, and Heleius. Perseus had also founded the city of Mycenae. When Perseus and Andromeda died, Athena placed them both in sky as constellations. Andromeda' parents had also been placed in the sky, as well as the sea monster as Cetus. One of Perseus' descendants was to become the greatest hero in Greek mythology, Heracles.

To read about Perseus' children and his descendants, see the House of Argolis, Perseïds.

There is another alternative legend to Perseus and Medusa, as told by Diodorus Siculus (Diodorus of Sicily). Diodorus wrote the Library of History in the 1st century BC, which contained a mixture of history and myths.

According to Diodorus, the Gorgons were no monsters, but were a race of woman warriors, similar those of the Amazons, but they seemed to be of different, because the two were enemies. The two races were rivals in the western part of Libya. The Gorgons probably lived further west than the Amazons.

Normally, most classical authors say that the home of the Amazons were in the east, around the region of the Thermodon River in Pontus (a region in Asia Minor), but Diodorus tried to tell his readers that the others were wrong in their assumptions. Between the Amazons and the Gorgons were the Atlantians, who were constantly in war against the Gorgons.

The Amazons under their queen, Myrina, had conquered the Atlantians, when they destroyed Cernê, one of cities of the Atlantians. The Amazons had later came to the aid of the Atlantians, when the Gorgons were repeatedly raided their land. A great battle was fought, where the Amazons defeated and subdued the Gorgons in several battles. In the last battle, Myrina broke the power of the Gorgons, where they later group fled.

Generations later, the Gorgons regained their former power, under the reign of their own queen – Medusa. It was at this period, that Perseus began his own campaign against the Gorgons. In the battle that followed, Perseus killed Medusa and her Gorgons were defeated.

The Gorgons were completely destroyed, when Heracles, a descendant of Perseus, set out in his 10th labour, where he built the pillars at the end of Libya.