HMS L11 was a British L class submarine built by Vickers, Barrow. She was laid down on 17 January 1917 and was commissioned on 27 June 1918. HMS L11 was converted along with HMS L12 into a minelayer. These two submarines were the only two of the L class submarine group 1 to be converted. The rest of the L class converted were of group 2 design. HMS L11 was sold in February 1932.