The Iteso are a Nilotic ethnic group in eastern Uganda and western Kenya. Teso refers to the traditional homeland of the Iteso, and Ateso is their language.

The Nilotic peoples are people indigenous to the Nile Valley who speak Nilotic languages. They inhabit South Sudan, Sudan, Ethiopia, Uganda, Kenya, the eastern border area of Democratic Republic of the Congo, Rwanda, Burundi and Tanzania. Among these are the Burun-speaking peoples, Teso people also known as Iteso or people of Teso, Karo peoples, Luo peoples, Ateker peoples, Kalenjin peoples, Karamojong people also known as the Karamojong or Karimojong, Datooga, Dinka, Nuer, Atwot, Lotuko, and the Maa-speaking peoples.