SS Calgarian was an Allan Line steam turbine ocean liner that was built in 1914 and converted into a Royal Navy armed merchant cruiser. Until 1916 she served with the 9th Cruiser Squadron, patrolling off West Africa and then off the east coast of the United States. She spent the remainder of her career making transatlantic crossings between Canada and Britain. An Imperial German Navy U-boat sank her off Rathlin Island, Ireland on 1 March 1918. Three torpedoes hit her, and her sinking killed two officers and 47 ratings.