Riek Machar Teny Dhurgon (born 1953), is the first vice-president of the independent Republic of South Sudan.

Riek Machar obtained a PhD in mechanical engineering in 1984 and then joined the rebel Sudan People's Liberation Movement/Army (SPLM/A) during the Second Sudanese Civil War (1983–2005). Riek fell out with the SPLM/A leader John Garang in 1991 and formed a splinter group, the SPLM/A-Nasir. In 1997 Riek made a treaty with the Government of Sudan and become head of the government-backed South Sudan Defense Force (SSDF). In 2000 he left the SSDF and formed a new militia, the Sudan People's Democratic Forces (SPDF), and in 2002 rejoined the SPLA as a senior commander. After the death of John Garang in July 2005, Riek Machar became vice-president of the autonomous Southern Sudan. He became vice-president of South Sudan on 9 July 2011 when the country became independent.

Riek Machar Teny Dhurgon was born in Leer, Unity State in 1953, the 26th son of the chief of both Ayod and Leer. He was brought up as a member of the Presbyterian church. Riek belongs to the Dok section of the Nuer people. He trained as an Engineer at Khartoum University, and obtained a PhD in Philosophy and strategic planning from the University of Bradford in 1984.

John Garang de Mabior (June 23, 1945 – July 30, 2005) was a Sudanese politician and leader. From 1983 to 2005, he led the Sudan People's Liberation Army during the Second Sudanese Civil War, and following a peace agreement he briefly served as First Vice President of Sudan from January 2005 until he died in a July 2005 helicopter crash.

A member of the Dinka ethnic group, Garang was born into a poor family in Buk village in the upper Nile region of Sudan. An orphan by the age of ten, he had his fees for school paid by a relative, going to schools in Wau and then Rumbek. In 1962 he joined the first Sudanese civil war, but because he was so young, the leaders encouraged him and others his age to seek an education. Because of the ongoing fighting, Garang was forced to attend his secondary education in Tanzania. After winning a scholarship, he went on to earn a B.A.^{[clarification needed]} in economics in 1969 from Grinnell College in Iowa, USA. He was known there for his bookishness. He was offered another scholarship to pursue graduate studies at the University of California, Berkeley, but chose to return to Tanzania and study East African agricultural economics as a Thomas J. Watson Fellow at the University of Dar es Salaam (UDSM). At UDSM, he was a member of the University Students' African Revolutionary Front. However, Garang soon decided to return to Sudan and join the rebels.^{[citation needed]} There is much erroneous reporting that Garang met and befriended Yoweri Museveni, future president of Uganda, at this time; while both Garang and Museveni were students at UDSM in the 1960s, they did not attend at the same time.