'Viper' was a German unrealised plan for an offensive to the north from East Prussia along the coast of Lithuania past Memel in an effort to pierce the Soviet front and so re-establish a land link with the forces of Generaloberst Ferdinand Schörner’s Heeresgruppe 'Nord' cut off in Kurland (autumn 1944).

The plan was expressly forbidden by Adolf Hitler on 26 October on the grounds that the plan had no chance of success.