POLYBOIA (or Polyboea) was a Spartan maiden who was granted immortality (apotheosis) as a demi-goddess in the retinue of Artemis. Her name, meaning "Of Many-Cows," was a compliment of beauty, for the fairest girls would win their fathers a high bride price payable in cattle.

She was probably closely identified with Phylonoe., another Spartan demi-goddess.

Pausanias, Description of Greece 3. 19. 4 (trans. Jones) (Greek travelogue C2nd A.D.) :
"On the altar [of Apollon at Amyklai near Sparta] are wrought in relief . . . the Moirai (Fates) and Horai (Seasons), and with them Aphrodite, Athena and Artemis. They are carrying to heaven Hyakinthos (Hyacinthus) and Polyboia, the sister, they say, of Hyakinthos, who died a maid."

According to Hesychius Polyboia was a goddess identified with Artemis or Persephone.

Sources:

• Pausanias, Description of Greece - Greek Travelogue C2nd A.D.

Other references not currently quoted here: Hesychius s.v. Polyboia