Thanatos is one of Saint Seiya's major antagonists, created by Masami Kurumada as an adaptation of the Greek god of the same name. He's the personification of death itself and twin brother to Hypnos, god of sleep. While technically subordinate to Hades, the ruler of the Underworld, Thanatos is a full deity and sworn enemy of Athena, protector of Earth.
Kurumada introduced him late in the Hades arc (volume 27), portraying him as cruel, merciless, and casually murderous. After losing to Athena in the 18th century, he and Hypnos were sealed away—Thanatos spent 243 years locked in a box stamped with Athena's seal until a curious three-year-old Pandora opened it. That's when he announced Hades's resurrection and informed her she'd be serving them from then on.
Thanatos and Hypnos look almost identical, with one key difference: Thanatos has silver eyes and hair while Hypnos has gold. A strange star marks his forehead. Unlike his calmer, more calculating twin, Thanatos has a hair-trigger temper and tends to act recklessly when angry.
He makes his home in Elysion, where he hangs out with Hypnos and a bunch of nymphs, waiting for Hades's orders. When the Saints of Athena showed up trying to save their goddess and stop Hades's Greatest Eclipse, Thanatos fought them hard.
The anime was way behind on this—he appeared in the opening credits starting around episode 128, but didn't get a full appearance until 2008, sixteen years after Kurumada first drew him. From episode 142 onward, the opening finally showed what he actually looked like.
Content compiled by AnimeList.moe from publicly available sources.
