Thanatos (死を司る神 タナトス, Shi o tsukasadoru kami Tanatosu?) is the god of Death and the twin brother of Hypnos. In Kurumada's original manga, their only differences are Thanatos' silver hair and eyes, as well as a pentagram star on his forehead, although the silver color of his hair and eyes is ignored in Lost Canvas, both manga and anime. Thanatos said that his body was Tartarus itself.
He is able to give a fraction of his own power to other Specters, and has direct command over Nasu Veronica, who shares the pentagram on his forehead. As a God he is capable of multiple feats, using Tartarus' Phobia (タルタロズフォビア, Tarutarozu Fobia?), Thanatos can summon a large number of souls that attacks the enemy and with Terrible Providence (テリブルプロビデンス, Teriburu Purobidensu?), Thanatos creates a powerful energy blast capable of destroying even the Gold Cloths, he is capable of summoning gigantic monsters resembling chess pieces to battle for him, or open the Godly Path, an space resembling the universe that destroys everything that is not a God in its interior. In his fight against Cancer Manigoldo and the Pope Sage, his host body is killed by Manigoldo, and his soul sealed by Sage inside a Holy Coffer empowered by Athena.