The 21st Waffen Mountain Division of the SS Skanderbeg (1st Albanian) was a German mountain infantry division of the Waffen-SS, the armed wing of the German Nazi Party that served alongside, but was never formally part of, the Wehrmacht during the Second World War. The division was developed around the nucleus of an ethnic Albanian battalion which had briefly seen combat against the Yugoslav Partisans in eastern Bosnia as part of the 13th Waffen Mountain Division of the SS Handschar (1st Croatian). Composed of Muslim Albanians with mostly German and Yugoslav Volksdeutsche (ethnic German) officers and non-commissioned officers, it was given the title Skanderbeg after medieval Albanian lord George Kastrioti Skanderbeg, who defended the region of Albania against the Ottoman Empire for more than two decades in the 15th century.

Skanderbeg never reached divisional strength, being at most a brigade-sized formation of around 6,000 to 6,500 troops. In May 1944, members of the division arrested 281 Jews in Pristina and handed them over to the Germans, who transported them to the Bergen-Belsen concentration camp, where many were killed. The division itself was better known for this action and for murdering, raping, and looting in predominantly Serb areas than for participating in combat operations on behalf of the German war effort. Its only significant military actions took place during a German anti-Partisan offensive in Montenegro in June and July 1944. Following those operations, the unit was deployed as a guard force at the chromium mines in Kosovo, where it was quickly overrun by the Partisans, leading to widespread desertion. Reinforced by German Kriegsmarine personnel and with less than 500 Albanians remaining in its ranks, it was disbanded on 1 November 1944. The remaining members were incorporated into the 7th SS Volunteer Mountain Division Prinz Eugen. After the war, divisional commander SS-Brigadeführer und Generalmajor der Waffen-SS August Schmidhuber was found guilty of war crimes by a court in Belgrade and was executed in 1947.