List of most successful U-boat commanders

The list of most successful U-boat commanders contains the top-scoring German U-boat commanders in the two World Wars based on their total tonnage sunk.

The tonnage figures (and sometimes the number of ships sunk) is still being debated among historians. This is often due to convoy battles at night when an attacking "wolfpack" fired torpedoes into the convoy and two (sometimes more) commanders claimed the same ship. Although post-war research has clarified most of those claims, some are still in question.

World War I
This list contains the most successful German U-boats commanders during the First World War based on total tonnage. Only sunk commercial vessels are included, not military (warships) nor damaged ships.

World War II
This list contains the most successful German U-boats commanders during the Second World War based on total tonnage. Only sunk commercial vessels are included, not military (warships) nor damaged ships.

The Aces of the Deep were the ten German U-Boat commanders during World War II who sank the most enemy merchant ships during their naval services, ranked according to the total tonnage of the ships they sank. The term is related to flying ace, a World War I name for a pilot who shot down five or more enemy planes. The currently accepted list is as follows: