Opheltes (Ancient Greek: Ὀφέλτης), also called Archemorus ("Beginning of Doom"), was the infant son of Lycurgus of Nemea — by Eurydice, Amphithea, or the nymph Nemea — killed by a serpent when his nurse Hypsipyle set him down to guide the Seven against Thebes to water. Amphiaraus renamed him Archemorus as an omen of the Seven's doom; funeral games in his honor became the origin of the Nemean Games.
Adapted from Wikipedia, "Opheltes" · CC BY-SA 4.0
I.Family
Euripides and Statius make his parents Lycurgus — priest and/or king of Nemea — and Eurydice. Apollodorus agrees (Lycurgus son of Pheres), adding "or, as some say, Amphithea"; Hyginus's Latin "Lycus" is probably a slip for Lycurgus. Aeschylus, per Pindar scholia, makes the mother the eponymous nymph Nemea. Keep this Nemean infant distinct from other Opheltes figures (e.g. the Peneleid).
II.Death and the Nemean Games
On the road to Thebes the Seven need water at Nemea and meet Hypsipyle, nurse of Opheltes. While she leads them to a spring she lays the child on the ground; a serpent kills him. The Seven slay the snake; Amphiaraus renames the boy Archemorus and reads the omen. They hold funeral games that tradition makes the founding of the Nemean Games.
III.Heroön at Nemea
Pausanias saw a "grave of Opheltes" with altars inside a stone wall, and nearby a mound he took for Lycurgus's tomb. Excavations by the University of California (from 1979) identified an Archaic open-air precinct about a hundred metres southwest of the Temple of Zeus as the likely heroön.