The South Irish Horse was a Special Reserve cavalry regiment of the British Army. Formed as an Imperial Yeomanry regiment in 1902 as the South of Ireland Imperial Yeomanry, it perpetuated a unit formed during the Second Boer War. It transferred to the Special Reserve (Cavalry) in 1908 and was renamed as the South Irish Horse. Having taken part in the fighting of World War I, it was disbanded after Irish Independence in 1922.