Eurydice

Eurydice was the Auloniad wife of musician Orpheus, who loved her deeply. On their wedding day, he played joyful songs as his bride danced through the meadow. One day, Aristaeus pursued Eurydice, who stepped on a viper, was bitten, and died.
Grief-stricken, Orpheus played and sang so mournfully that all nymphs and deities wept and advised him to journey to the Underworld to retrieve her, which he willingly did. His music softened the hearts of Hades and Persephone, his singing so sweet that even the Erinyes wept, and he was permitted to take her back to the world of the living. In another version, Orpheus played his lyre to lull Cerberus, the guardian of Hades, to sleep, after which Eurydice was allowed to return with him.
Either way, there was one condition: he must walk in front of her and not look back until both had reached the upper world. Soon, he began to doubt her presence, suspecting Hades had deceived him. Just as he reached the portals of Hades and daylight, he turned to look at her, and because Eurydice had not yet crossed the threshold, she vanished back to the Underworld. When Orpheus was later killed by the Maenads at Dionysus's command, his soul entered the Underworld, where he reunited with Eurydice.
This version of the story dates to Virgil, who first introduced Aristaeus and the tragic ending. Other ancient sources portray Orpheus's underworld visit differently; according to Phaedrus in Plato's Symposium, the infernal deities merely "presented an apparition" of Eurydice. Plato depicts Orpheus as cowardly; instead of choosing death to be with his beloved, he offended the deities by attempting to bring her back alive. Since his love wasn't "true"—he wouldn't die for it—the deities punished him by showing only an apparition of his wife in the underworld and later having him killed by women.
The Eurydice story may be a later addition to Orpheus myths. Notably, the name Eurudike ('she whose justice extends widely') recalls cult-titles of Persephone. The myth possibly derived from another Orpheus legend where he travels to Tartarus and charms the goddess Hecate.
Eurydice's tale has numerous cultural parallels worldwide, including the Japanese myth of Izanagi and Izanami, the Mayan myth of Itzamna and Ixchel, and the Indian myth of Savitri and Satyavan. While often compared to the Akkadian/Sumerian myth of Inanna's descent, that story actually parallels Persephone's abduction by Hades, as both explain seasonal changes. The biblical account of Lot's wife, turned to salt for looking back at her fleeing town, is frequently compared to Orpheus and Eurydice's story.