The title of the senior Russian or Soviet intelligence officer in a particular country, undertaking duties identical to a Central Intelligence Agency station chief or a Secret Intelligence Service station commander. Usually working under diplomatic cover, though necessarily at a rank that reflects his true status, the rezident will have a staff of subordinates and may call upon the assistance of cooptees.
During the Cold War, the senior illegal in a given area was designated the illegal rezident and fulfilled much the same role as his legal counterpart but without diplomatic immunity.