Olusegun Obasanjo (born March 5, 1937) is the president of Nigeria (since 1999). A born-again Christian of Yoruba extraction, Obasanjo was a career soldier before serving twice as his nation's head of state, once as a military ruler and again, currently, as elected president.

Obasanjo was born in Abeokuta, Ogun State, and he enlisted into the army at the age of 18. He trained at Aldershot and was commissioned as an officer. He participated in the military coup of 1975, led by Murtala Ramat Mohammed, and was named Murtala's deputy in the new government. When Mohammed was assassinated in an attempted coup in 1976, Obasanjo replaced him as head of state. He served until 1979, when he handed power back to civilian authorities and retired, becoming the first leader in Nigerian history to surrender power willingly. In late 1983, however, the military seized power again. Obasanjo, being in retirement, did not participate in that coup, and did not approve of it.

During the dictatorship of Sani Abacha (1993-1998), Obasanjo spoke out against the human rights abuses of the regime, and was imprisoned. He was released only after Abacha's sudden death on 8 June 1998. It was after his release from prison that Obasanjo announced that he was now a born-again Christian, a factor that has been crucial in recent years in cementing his popularity in Nigeria's southern states where Christianity is the predominant faith.

In the 1999 elections, the first for sixteen years, he decided to run for the presidency as the candidate of the People's Democratic Party. Obasanjo won with 62.6 percent of the vote, sweeping the strongly Christian South-East and the predominantly Muslim north, but decisively lost his home region, the south-west, to his fellow-Yoruba and fellow-Christian, Olu Falae, the only other candidate. It is thought that lingering resentment among his fellow-Yorubas about his previous administration of 1976 to 1979, after which he handed power over to a government dominated by northerners rather than by Yorubas, contributed to his poor showing among his own people.

Obasanjo was handily reelected in 2003 in a tumultuous election that had religious overtones, his main opponent (fellow former military ruler General Muhammadu Buhari) being a Muslim who drew his support mainly from the Muslim north. Capturing 61.8 percent of the vote, Obasanjo defeated Buhari by more than 11 million votes. Buhari and other defeated candidates (including Chukwuemeka Odumegwu Ojukwu, the former Biafran warlord of the 1960s), claimed that the election was fraudulent. International observers from the British Commonwealth were more nuanced in their judgement. They concluded that while there had been incidents of fraud on both sides, Obasanjo's margin of victory was so huge that electoral malpractice would not have changed the result. Much more worrying was the increasing polarization of Nigeria along religious lines. Obasanjo made a spectacular sweep of the Christian South, including the south-west where he had lost four years earlier, but lost considerable ground among Muslims in the North. For a nation evenly divided between Christians and Muslims, such a trend was seen by many as particularly disturbing.