In classical Freudian psychoanalytic theory, the death drive ("Todestrieb") is the drive towards death, self-destruction and the return to the inorganic: 'the hypothesis of a death instinct, the task of which is to lead organic life back into the inanimate state'. It was originally proposed by Sigmund Freud in 1920 in Beyond the Pleasure Principle, where in his first published reference to the term he wrote of the 'opposition between the ego or death instincts and the sexual or life instincts'. The death drive opposes Eros, the tendency toward survival, propagation, sex, and other creative, life-producing drives. The death drive is sometimes referred to as "Thanatos" in post-Freudian thought, complementing "Eros", although this term was not used in Freud's own work, being rather introduced by one of Freud's followers, Wilhelm Stekel.

The Standard Edition of Freud's works in English confuses two terms that are different in German, Instinkt ("instinct") and Trieb ("drive"), often translating both as instinct. 'This incorrect equating of instinct and Trieb has created serious misunderstandings'. Freud actually refers to the "death instinct" as a drive, a force that is not essential to the life of an organism (unlike an instinct) and tends to denature it or make it behave in ways that are sometimes counter-intuitive. The term is almost universally known in scholarly literature on Freud as the "death drive", and Lacanian psychoanalysts often shorten it to simply "drive" (although Freud posited the existence of other drives as well).

Sigmund Freud (German pronunciation: [ˈziːkmʊnt ˈfʁɔʏt]), born Sigismund Schlomo Freud (6 May 1856 – 23 September 1939), was an Austrian neurologist who founded the discipline of psychoanalysis. Freud's family and ancestry were Jewish. Freud always considered himself a Jew even though he rejected Judaism and had a critical view of religion. Freud's parents were poor, but ensured his education. Freud was an outstanding pupil in high school, and graduated the Matura with honors in 1873. Interested in philosophy as a student, Freud later turned away from it and became a neurological researcher into cerebral palsy, Aphasia and microscopic neuroanatomy.

Freud went on to develop theories about the unconscious mind and the mechanism of repression, and established the field of verbal psychotherapy by creating psychoanalysis, a clinical method for treating psychopathology through dialogue between a patient (or "analysand") and a psychoanalyst. Though psychoanalysis has declined as a therapeutic practice, it has helped inspire the development of many other forms of psychotherapy, some diverging from Freud's original ideas and approach. Freud postulated the existence of libido (an energy with which mental process and structures are invested), developed therapeutic techniques such as the use of free association (in which patients report their thoughts without reservation and make no attempt to concentrate while doing so), discovered the transference (the process by which patients displace on to their analysts feelings based on their experience of earlier figures in their lives) and established its central role in the analytic process, and proposed that dreams help to preserve sleep by representing as fulfilled wishes that would otherwise awake the dreamer. He was also a prolific essayist, drawing on psychoanalysis to contribute to the interpretation and critique of culture.