The RMS Walmer Castle was a Royal Mail Ship of the Union-Castle Line in service between London, England and Cape Town, South Africa between 1902 and 1930.

Her service was interrupted in 1917 when she was requisitioned by the government to serve as a troop transport, transporting troops from South Africa and later in the North Atlantic, painted in a camouflaged dazzle scheme.

In 1919, she made two voyages between Liverpool and New York before returning to her mail run.

Among her notable passengers were poet Rudyard Kipling and politician Lord Gladstone, the first Governor General of South Africa.

Lord Alfred Milner and his wife Violet traveled from England to South Africa aboard the Walmer Castle in 1924.