The Odin-class submarine was a class of nine submarines developed and built for the Royal Navy (RN) in the 1920s. The prototype, Oberon, was followed by two boats originally ordered for the Royal Australian Navy, but transferred to the RN in 1931 because of the poor economic situation in Australia, and six modified boats ordered for the RN. Three modified boats were built for the Chilean Navy as the Capitan O'Brien-class submarines in 1929.

The British L-class submarine was originally planned under the emergency war programme as an improved version of the British E-class submarine. The scale of change allowed the L class to become a separate class.