Adolf Cornelius Piening (16 September 1910 in Süderende on Föhr – 15 May 1984 in Kiel) was a Kapitänleutnant with the Kriegsmarine during World War II. He commanded the Type IXC U-boat , sinking twenty-six ships on nine patrols, for a total of of Allied shipping, to become the nineteenth highest scoring U-Boat ace of World War II, and receiving 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.