HMS Cyclops was the lead ship of the Cyclops-class breastwork monitors built for the Royal Navy during the 1870s. The ships were ordered to satisfy demands for local defence during the war scare of 1870, but the pace of construction slowed down tremendously as the perceived threat of war declined. The ship spent most of her career in reserve; her only sustained period in commission was four months in Portland Harbour, during the Russo-Turkish War in 1878 when the British were trying to force the Russians to end the war without allowing them to seize Constantinople. Cyclops was sold for scrap in 1903.