HMS Ultor (P53) was a Royal Navy U-class submarine built by Vickers-Armstrong at Barrow-in-Furness, launched in 1942, and part of the third group of the class.

The damaged tanker was beached and later torpedoed again by HMS Uproar.

Ultor survived the war and returned to the shore establishment HMS Dolphin at Gosport, and after a brief refit joined the 6th Flotilla at Blyth.

When Blyth was closed Ultor went around to Rothesay, with the depot ship HMS Cyclops.

She spent some time as an ASDIC training target, then was put into reserve at Londonderry.