Josef Diefenthal (5 October 1915 – 13 April 2001) was a mid-ranking commander in the Waffen-SS of Nazi Germany and a war criminal during World War II. He was a recipient of the Knight's Cross of the Iron Cross on 5 February 1945 for his actions during the Ardennes Offensive, while in command of the 3rd Battalion, 2nd SS Panzer Grenadier Regiment, SS Division Leibstandarte.