The Allies is an alliance made up of Americans, British, Soviets and others who fought against the Axis powers.
In the original timeline they won the war, often attributed to the actions of William "B.J." Blazkowicz.
The New OrderEdit
In The New Order, they lost the war. The Allies' last great push was an all out attack by the OSA with the combined efforts of British and American air forces on Deathshead's compound in Poland. But they failed to kill Deathshead, and soon after New York City was destroyed by an atomic bomb and the US surrendered. RAF was completely decimated, London was destroyed by a series of bombings, and finally fell to the London Monitor. The Red Army was also completely decimated in Russia. With the fall of Moscow, the Soviet Union also fell to the Nazi regime.
The Allies represent the actual allies of the Second World War who fought against Nazi Germany and ultimately won the war. They use the flag of the USA as their symbol.
In most multiplayer scenarios, the Allies are traditionally on the offensive, trying to steal something valuable (e.g. treasure, ancient relic or secret documents) from the Axis, or to destroy an important objective (e.g. heavy military hardware).
Strangely, the allies can be seen equipped with the Venom Gun, which is the experimental Nazi weapon.