Fenian Ram is a submarine designed by John Philip Holland for use by the Fenian Brotherhood, the American counterpart to the Irish Republican Brotherhood, against the British. The Fenian Ram was the world’s first practical submarine. It was powered by a double acting Brayton Ready Motor which used kerosene fuel. It was able to dive & submerge successfully. The Ram's construction and launching in 1881 by the Delamater Iron Company in New York was funded by the Fenians' Skirmishing Fund. Officially Holland Boat No. II, the role of the Fenians in its funding led the New York Sun newspaper to name the vessel the Fenian Ram.

John Philip Holland was an Irish engineer who developed the first submarine to be formally commissioned by the US Navy, and the first Royal Navy submarine, Holland 1.