German submarine U-124 was a Type IXB U-boat of Nazi Germany's Kriegsmarine during World War II. She operated in the Atlantic as part of the 2nd U-boat flotilla, both west of Scotland and east of the eastern US coast. She was also present off northern South America.

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.