HMCS Protector was a large flat-iron gunboat commissioned and purchased by the South Australian government in 1884, for the purpose of defending the local coastline against possible attacks in the aftermath of the 'Russian scare', of the 1870s. She arrived in Adelaide in September 1884 and served in the Boxer Rebellion, World War I and World War II.

Flat-iron gunboats were a number of classes of coastal gunboats generally characterised by small size, low freeboard, the absence of masts, and the mounting of a single non-traversing large gun, aimed by pointing the vessel. They acquired their nickname from the physical similarity with the flat iron used for ironing clothes during the 19th century.