Rhea first appeared in full as an antagonist in the novel Wizard and Glass, the fourth book in Stephen King's Dark Tower series. She also appears in the Marvel comic book adaptation of the same name.
Rhea is a witch, who lived in Hambry with her cat, Musty. A malicious and sadistic woman, she played a role in the downfall of the Affiliation, as well as the death of Susan Delgado and her unborn child.
The Gunslinger Born
In Dark Tower: The Gunslinger Born, Rhea is entrusted with "Maerlyn's Grapefruit", one of the coloured magical orbs which comprise Maerlyn's Rainbow. She quickly becomes obsessed with the artifact, and the powers of divination contained within it.
She was also given the task of physically examining Susan Delgado for evidence of her virginity, after the young girl was promised to Mayor Thorin. Bitter and envious of Susan, Rhea hypnotised the girl during the examination and cursed her, so that after losing her virginity she would cut off all of her hair. When Susan sleeps with Roland instead of the Mayor, the gunslinger fortunately prevents her from doing so, infuriating Rhea in the process.
Along with Susan's aunt Cordelia, Rhea was instrumental in drumming up resentment and anger toward Susan among the residents of Hambry, eventually culminating in Susan and her unborn baby being burned alive as a sacrifice on Reaping Night.
In Other Media
Along with her main appearance in Wizard and Glass, Rhea also makes a cameo appearance in the fantasy novel Eyes of the Dragon,