Prosper Graf zu Castell-Castell (4 September 1920 – 3 January 1989) was a highly decorated Oberst in the Wehrmacht during World War II. He was also a recipient of the Knight's Cross of the Iron Cross. The Knight's Cross of the Iron Cross was awarded to recognise extreme battlefield bravery or successful military leadership. Prosper Graf zu Castell-Castell was captured by American forces in May 1945 and was released in late June 1945.