The Luo are several ethnically and linguistically related Nilotic ethnic groups in Africa that inhabit an area ranging from South Sudan and Ethiopia, through Northern Uganda and eastern Congo (DRC), into western Kenya, and the Mara Region of Tanzania. Their Luo languages belong to the Nilotic group and as such form part of the larger Eastern Sudanic family.

Luo groups in South Sudan include the Shilluk, Anuak, Pari, Acholi, Balanda Boor, Thuri, Maban, and Luwo, and those in Uganda include the Alur, Acholi, Lango, Padhola, and Joluo.

The Joluo and their language Dholuo are also known as the "Luo proper", being eponymous of the larger group. The level of historical separation between these groups is estimated at about eight centuries. Dispersion from the Nilotic homeland in South Sudan was presumably triggered by the turmoils of the Muslim conquest of Sudan. The migration of individual groups over the last few centuries can to some extent be traced in the respective group's oral history.