HMS Unbending (P37) was a Royal Navy U-class submarine built by Vickers-Armstrong at Barrow-in-Furness, and part of the third group of that class. So far she has been the only ship of the Royal Navy to bear the name Unbending.
Unbending spent most of her wartime career in the Mediterranean, where she sank the Italian merchants Alga, Citta di Bergamo, Cosenza and Beppe, the Italian auxiliary minelayer Eritrea and the Italian destroyer Giovanni da Verazzano. She also sank the Italian ship Lupa II with gunfire. Unbending had first fired two torpedoes but these were evaded. Unbending also damaged the Italian passenger / cargo ship Viminale, the Italian merchant Carlo Margottini (the former Yugoslavian Bled), and the Italian passenger ship Carlo Margottini. This ship ran ashore and is not listed as a war loss so was most likely salvaged and returned to service.