'Otto' (iii) was the German original codename under which the invasion of the USSR was planned for implementation in May 1941 (June/5 December 1940).

The plan was later modified in the light of Adolf Hitler’s Führerweisung Nr 21 of 18 December 1940 to become 'Barbarossa' with reduced emphasis on the capture of Moscow but increased emphasis on the destruction of the Soviet armed forces.