HMCS Rainbow was an Apollo-class protected cruiser built for Great Britain's Royal Navy as HMS Rainbow entering service in 1892. Rainbow saw time in Asian waters before being placed in reserve in 1909. In 1910 the cruiser was transferred to the Royal Canadian Navy for service on the west coast. At the outbreak of the First World War, Rainbow was the only major Canadian or British warship on the western coast of North America. Due to age, the cruiser was taken out of service in 1917 and sold for scrap in 1920 and broken up.

The Apollo class were second-class protected cruisers designed by Sir William White and built for the Royal Navy in the late 19th century. Twenty-one ships of this class were built, making it the largest single class of steel cruisers ever built for the Royal Navy to the same design.