HMS Unique was a U-class submarine of the Royal Navy, of the second group of that class, built by Vickers Armstrong, Barrow-in-Furness.

She also damaged the Italian cargo ship Arsia, which was later declared a total loss.

On 5 January 1942, she made an unsuccessful attack on the Italian battleship Littorio.

[1] Unique left Holy Loch after a refit, for a patrol in the Bay of Biscay on 7 October 1942.

HMS Ursula was in the area on 10 October and reported hearing underwater explosions that led her to believe Unique was under attack, although the Germans made no claims of her sinking.