A further deed attributed to Perseus was his rescue of the Ethiopian princess Andromeda when he was on his way home with Medusa's head. Andromeda's mother, Cassiopeia, had claimed to be more beautiful than the sea nymphs, or Nereids; so Poseidon had punished Ethiopia by flooding it and plaguing it with a sea monster. An oracle informed Andromeda's father, King Cepheus, that the ills would cease if he exposed Andromeda to the monster, which he did. Perseus, passing by, saw the princess and fell in love with her. He turned the sea monster to stone by showing it Medusa's head and afterward married Andromeda.

Later Perseus gave the Gorgon's head to Athena, who placed it on her shield, and gave his other accoutrements to Hermes. He accompanied his mother back to her native Argos, where he accidentally struck her father, Acrisius, dead when throwing the discus, thus fulfilling the prophecy that he would kill his grandfather. He consequently left Argos and founded Mycenae as his capital, becoming the ancestor of the Perseids, including Heracles. The Perseus legend was a favourite subject in painting and sculpture, both ancient and Renaissance. (Benvenuto Cellini's bronze statue in Florence of Perseus with Medusa's head is especially famous.) The chief characters in the Perseus legend, Perseus, Cepheus, Cassiopeia, Andromeda, and the sea monster (Cetus), all figure in the night sky as constellations.

the last king of Macedonia (179–168), whose attempts to dominate Greece brought on the final defeat of Macedonia by the Romans, leading to annexation of the region.

The elder son of King Philip V of Macedonia, Perseus commanded troops in his father's wars against Rome (199) and Aetolia (189). After three years of intriguing against his brother Demetrius, accusing him of coveting the succession, Perseus in 180 persuaded the king to have Demetrius executed. On succeeding to the throne in 179, he extended his influence in Thrace and Illyria but made special efforts to win over the Greek world. To this end he resumed control of the Delphic Amphictyony, established excellent relations with Rhodes, and encouraged revolution in Aetolia and Thessaly. After subduing a revolt in Dolopia, he aroused widespread alarm in Greece by visiting Delphi with his army. In 172 Eumenes II of Pergamum incited Rome against Perseus's allegedly aggressive designs, thus precipitating the Third Macedonian War (Macedonian Wars) (171–168). Perseus held off the Romans for three years but in 168 lost the support of Genthius of Illyria, thus exposing his western flank. A Roman army forced him to fight at Pydna (Pydna, Battle of) (in southern Macedonia), where he was defeated by Lucius Aemilius Paullus. After marching as a captive in Aemilius Paullus's triumph (167), Perseus spent the brief remainder of his life in captivity. Perseus's failure revealed his inability to reconcile the needs of Macedonia with the reality of Roman predominance.