Major Robert Johnston, VC, was an Irish rugby union player and soldier. During the Second Boer War, Johnston was awarded the Victoria Cross while serving with the Imperial Light Horse. He played rugby for both Ireland and the British Lions. He is one of three Ireland rugby union internationals to have been awarded the Victoria Cross. The other two are Thomas Crean, who also served with the Imperial Light Horse in the Second Boer War, and Frederick Harvey who served in the First World War. Johnston, Crean and Harvey all played club rugby for Wanderers. In 1896 Johnston and Crean were also members of the same British Lions squad that toured South Africa . Johnston was also one of three alumni of King William's College to have been awarded the VC. The other two were George Stuart White and Robert Henry Cain. White served in the Second Anglo-Afghan War and Cain served in the Second World War.

The Johannesburg Light Horse Regiment, is a reserve armoured car reconnaissance unit of the South African Army.