Oskar Karl Gustav Adolf Prince of Prussia (27 July 1888 – 27 January 1958) was the fifth son of German Emperor Wilhelm II and Augusta Victoria of Schleswig-Holstein-Sonderburg-Augustenburg.

He was baptised in the chapel of the Royal Palace on the Spree Island in central Berlin and was named after King Oscar II of Sweden and Norway, who was also his godfather.

Future fighter ace Manfred von Richthofen witnessed the 22 August 1914, attack on Virton, Belgium, and wrote of Prinz Oskar's bravery and his inspirational leadership at the front of his regiment as they went into combat.

[7] In the early 1920s, his name was listed with other members of the general staff or the royal family accused of war crimes, and was condemned in the Press for applying for a colonel's pension from the Weimar Republic.

[8] During the 1930s, when the Hohenzollern family attempted to test the waters for a return to power through Nationalist Socialism, Oskar appears to have played along, and eventually was commissioned at Generalmajor zur Verfügung (rank equivalent to brigadier general, "available for assignment"), circa 1 March 1940.

As the family fell out of favour with Hitler (with the exception of Oskar's middle brother, August Wilhelm), it became evident that there would be no restoration of the monarchy through the Nazis.

Prinz Oskar was married on 31 July 1914 to Countess Ina-Marie Helene Adele Elise von Bassewitz (27 January 1888 – 17 September 1973).