German submarine U-518 was a Type IXC U-boat of the Nazi Germany's Kriegsmarine during World War II. She saw considerable success from her launch on 11 February 1942 until she was sunk on 22 April 1945. The U-boat was laid down at the Deutsche Werft in Hamburg as yard number 314 on 12 June 1941, and commissioned on 25 April 1942 with Fregattenkapitän Hans-Günther Brachmann in command. He was replaced on 19 August 1942 by Kapitänleutnant Friedrich-Wilhelm Wissmann. She sank nine ships and damaged three more in seven active patrols. U-518 had a crew of 56, and was by then commanded by Oberleutnant zur See Hans-Werner Offermann from 13 January 1944.

The Type IX U-boat was designed by Nazi Germany's Kriegsmarine in 1935 and 1936 as a large ocean-going submarine for sustained operations far from the home support facilities. Type IX boats were briefly used for patrols off the eastern United States in an attempt to disrupt the stream of troops and supplies bound for Europe. It was derived from the Type IA, and appeared in various sub-types.