HMS Unruly was a Royal Navy U-class submarine built by Vickers-Armstrong at Barrow-in-Furness.

Unruly spent most of her eventful wartime career in the Mediterranean, apart from a period on convoy escort duty off the North Cape.

Whilst serving in the Mediterranean, she sank the French merchant St Lucien, the Italian merchant Valentino Coda, twelve sailing vessels, including the Greek Aghios Giorgios, and the German minelayer Bulgaria.

She was attacked with four torpedoes, at least one of which hit the Italian submarine, which sank her with the loss of all 46 of her crew.

The crew of Unruly did not actually see the results of the attack, and initially believed they had missed and their target had escaped.