In Greek mythology, Phaethusa ("radiance") was a daughter of Helios and Neaera, the personification of the brilliant, blinding rays of the sun. With her sister, Lampetia, she guarded the cattle of Thrinacia[?].
... management" and "copy protection" systems:
Serial copy management system[?] (SCMS)
Macrovision
iTunes
Windows media player[?]
DRM and document restriction ...