First United States Army Group (often abbreviated FUSAG) was a fictitious (paper command) Allied Army Group in World War II prior to D-Day, part of Operation Quicksilver, created to deceive the Germans about where the Allies would land in France.

To attract Axis attention, prominent US general George S. Patton was placed in command of the fabricated formation.

First U.S. Army Group was activated in London in 1943 as the planning formation for the Allied invasion of France under General Omar Bradley.

Despite a lack of personnel, FUSAG continued to exist on paper as part of the deception of Operation Quicksilver.

Patton was considered by the Germans to be a formidable offensive commander; he was temporarily unemployed as punishment for slapping a battle-fatigued soldier in Sicily.