Leo, the Royal Cadet is a light opera with music by Oscar Ferdinand Telgmann. The libretto was by George Frederick Cameron. It was composed in Kingston, Ontario, Canada in 1889. The work centres on Nellie's love for Leo, a cadet at the Royal Military College of Canada who becomes a hero serving during the Anglo-Zulu War in 1879 between the British Empire and the Zulu Empire. The operetta focussed on typical character types, events and concerns of Telgmann and Cameron's time and place.

The story is loosely based on actual events. The character 'Colonel Hewett' is based on Colonel Edward Osborne Hewett, C.M.G. who served as the first Commandant of the Royal Military College of Canada 1875-86. The character of Leo, who leaves his sweetheart Nellie to fight the Zulus in Natal, and other cadets may be based on several early cadets who were decorated for valour. Huntley Brodie Mackay, a Royal Engineer was the first ex-cadet to win a Distinguished Service Order, served in Bechuanaland 1884-9 and as commanding royal engineer in West Africa 1887-9. Mackay fought tribes near Sierra Leone and became an acting administrator of the British East Africa Company. William Henry Robinson, Royal Engineer, the first ex-cadet to be killed in action, died while attempting to blow up the gate of a stockade at Tambi near Sierra Leone. Kenneth J.R. Campbell was the first ex-cadet to be mentioned in despatches for his part in the operation against the town of Brohemie, Niger Coast Protectorate. Sir George Norton Cory participated in operations in Natal, South Africa in 1899 and later edited 'The Diary of Reverend Francis Owen M. A., missionary with Dingaan in 1837-38 together with extracts from the writings of the interpreters in Zulu, Messrs. Hulley and Kirkman'(Cape Town, South Africa: Van Riebeech Society, 1926).

The character Cetcho, a Zulu chief is based on Cetshwayo. The Battalion Sergeant Major character who sings The Royal Cadet - The Battalion Sergeant Major was the senior cadet at the Royal Military College of Canada from 1878–1923 and 1934-42. Since 1952, the senior cadet has been known as a Cadet Wing-Commander.