1939 1940 1941 1942 1943 1944 1945 Widder (HSK 3) was an auxiliary cruiser (Hilfskreuzer) of Nazi Germany's Kriegsmarine that was used as a merchant raider in the Second World War.

Her Kriegsmarine designation was Schiff 21, to the Royal Navy she was Raider D. The name Widder (Ram) represents the constellation Aries in German.

Built at Howaldtswerke, Kiel, she was launched in 1929 as the cargo ship Neumark for the Hamburg America Line (HAPAG).

On 13 May Widder encountered the British submarine HMS Clyde on the surface, exchanging gunfire for more than an hour, with no hits for either side.

On 21 August 1940, 800 miles west of the Canary Islands, she sank Anglo Saxon, which had been carrying coal from Newport, Wales, to Bahía Blanca, Argentina.