Thanatos has a second life inside modern psychology that most people encounter before they ever meet the Greek personification directly, and it rests on a widely repeated claim that does not entirely hold up. Sigmund Freud, in Beyond the Pleasure Principle (1920), proposed a death drive, Todestrieb, standing opposite the life preserving drives he grouped under Eros, and popular summaries ever since have paired the two as Eros and Thanatos, as though Freud himself had chosen the Greek god's name for his own concept. Historians of psychoanalysis note that Freud's own German texts make only sparing, inconsistent use of the actual word Thanatos, and that the tidy pairing with Eros was cemented mainly by his followers and by later popularizers rather than fixed by Freud in his founding papers, a gap between the coinage's popular attribution and its documented textual history that specialists still point out when the phrase is used as though it were a direct Freudian quotation.
The related word thanatology, the systematic study of death, dying, and grief, belongs to a separate and better documented history, usually traced to the early twentieth century biologist Elie Metchnikoff, who wrote on aging and mortality as part of his broader project of orthobiosis, the science of a properly lived and ended life. The field grew substantially in the later twentieth century into a recognized area of medical and psychological research, carrying the old god's name into hospital ethics committees and palliative care literature, a destination considerably removed from Sarpedon's battlefield or the stage of Euripides.