Identification with the aggressor stands as one of the more consequential and contested mechanisms in the depth-psychological canon. Originally crystallized in Anna Freud’s 1936 formulation and anticipated in Sándor Ferenczi’s clinical investigations of the late 1920s and early 1930s, the concept names the process by which a subject under threat internalizes the posture, values, or destructive agency of the threatening other — transforming passive suffering into active imitation as a means of psychic survival. The corpus reveals at least two distinct theoretical trajectories. The first, largely ego-psychological, reads the mechanism as a developmental stage in superego formation: the Oedipal child, unable to sustain hostility toward the punishing father, represses aggression and identifies with paternal authority, producing the authoritarian character. The second, rooted in Ferenczi’s trauma theory and carried forward by Kalsched, van der Hart, and the dissociation theorists, treats identification with the aggressor as a post-traumatic phenomenon in which the victim’s nascent self is colonized by the perpetrator’s perspective — yielding self-persecution, repetition compulsion, and the dissociative structures that come to tyrannize the inner world. Grof’s LSD research independently corroborates that traumatic reliving requires working through the aggressor role as well as the victim role. Tensions persist between intrapsychic and relational readings, and between developmental and traumatogenic framings.