Joseph Lagu (born 21 November 1931, in a hamlet called Momokwe in Moli, northern region of , about 80 miles south of Juba, Sudan, currently South Sudan) is a South Sudanese military figure and politician. He belongs to the Madi ethnic group of Eastern Equatoria State, South Sudan. In May 1960 he graduated from the military college in Omdurman and was commissioned as a second lieutenant in the Sudanese Army and was posted to Shendi with the 10th Brigade, Northern Command. In the period 1978–1979, Lagu served as the second President of the .