In Greek mythology, Erytheia (also Erytheis or Erythia; Ancient Greek Ἐρυθεία / Ἐρυθεΐς) is one of the Hesperides, the nymphs who tend Hera's golden-apple garden in the far west. Apollonius of Rhodes names her with Aigle and Hespere; Apollodorus lists Aigle, Erytheia, Hesperia, and Arethusa. Her name evokes the red of sunset. She is not the island Erytheia associated with Geryon in the far west.
Adapted from Wikipedia, "Hesperides" · CC BY-SA 4.0
I.Parentage and catalogue
Ancient sources disagree on how many Hesperides there were and who their parents were. They are variously daughters of Night (Nyx), of Nyx and Erebus, of Atlas and Hesperis, of Phorcys and Ceto, of Zeus and Themis, or of Hesperus.
Apollonius names three — Aigle, Erytheis, and Hespere (or Hespera). Apollodorus gives four: Aigle, Erytheia, Hesperia, and Arethusa. Hyginus and Servius preserve related lists in which Erytheia or Erythia appears among the evening maidens who guard the golden fruit.
II.The garden
The Hesperides tend a blissful orchard at the edge of Oceanus in the far west, where a tree or grove bears golden apples given to Hera as a wedding gift by Gaia. An immortal, hundred-headed dragon, Ladon, helps guard the fruit. The sisters are also remembered as singers — Euripides calls them "minstrel maids."
Erytheia herself has no separate quest narrative; her role is that of a named guardian of the garden whose sunset epithet marks the western setting of Heracles' eleventh labour.
III.Homonyms
This atlas entry (erytheia-hesperid) is the Hesperid nymph. Distinct from Erytheia the western island (or red land) linked to Geryon's cattle in the Heracles cycle — a place-name, not this nymph — and from other "red" toponyms in the far west.