Sihayo kaXongo (c. 1824 – 2 July 1883) was a Zulu inKosi (chief). In some contemporary British documents he is referred to as Sirhayo or Sirayo. He was an inDuna (commander) of the iNdabakawombe iButho (social age group and regiment) and supported Cetshwayo in the 1856 Zulu Civil War. Under Cetshwayo, Sihayo was a chief of a key territory on the border with the British Colony of Natal and had a seat on the iBandla (royal council). Sihayo was an Anglophile who wore European clothes and maintained friendly relations with trader James Rorke who lived nearby at Rorke's Drift. By 1864, Sihayo was head of the Qungebe tribe and that year agreed a new western border of the kingdom with Boer leader Marthinus Wessel Pretorius.
In 1878 two of Sihayo's wives were found to be cheating, were attacked by Sihayo's family, and fled to Natal. Sihayo's sons and brother launched a cross-border raid which captured and executed them. The British authorities objected and demanded Sihayo's family be handed over to face British justice. Cetshwayo refused and the incident became a casus belli of the 1879 Anglo-Zulu War. Sihayo's kraal was attacked on 12 January and one of his sons killed. Sihayo had taken most of his men to Ulundi to join the royal army. The Zulu defeated the British at the Battle of Isandlwana, which some of Sihayo's men participated in, but lost the war in July. The Zulu kingdom was broken up after the war and Sihayo lost his land. Sihayo was killed in July 1883 when Ulundi was overrun by the forces of Zibhebhu kaMaphitha during the Third Zulu Civil War.