HMS E1 was a British E-class submarine that was built by Chatham Dockyard and cost £101,700. E1 was laid down on 14 February 1911. She was launched on 9 November 1912 and was commissioned on 6 May 1913. During World War I she was part of the British submarine flotilla in the Baltic.

The British E-class submarines started out as improved versions of the British D-class submarine. The E class served with the Royal Navy throughout World War I as the backbone of the submarine fleet. The last surviving E class submarines were withdrawn from service by 1922.