The two Nigerian Military Juntas of 1966-1979 and 1983-1998 were a pair of military dictatorships in Nigeria that were led by the Nigerian military, having a chairman or president in charge.
Nigerian military juntas of 1966–79 and 1983–98 Wikipedia
Nigeria's first military junta began following the 1966 Nigerian coup d'état which overthrew Prime Minister Alhaji Sir Abubakar Tafawa Balewa. Major General Johnson Aguiyi-Ironsi was made the Head of the Federal Military Government of Nigeria, but was soon overthrown and murdered in a coup in July of the same year.
Aguiyi-Ironsi was succeeded by General Yakubu Gowon, who established a Supreme Military Council. Gowon held power until July 1975, when he was overthrown in a bloodless coup.
Brigadier (later General) Murtala Mohammed, who succeeded Gowon. Months later, in February 1976, Mohammed was assassinated by Buka Suka Dimka and others in a violent coup attempt, but the plotters failed to kill Olusẹgun Ọbasanjọ, who then succeeded Mohammed as head of state.
The Supreme Military Council was formally dissolved when Ọbasanjọ handed power to the elected Shehu Shagari, ending the military regime and establishing a Nigerian Second Republic.
Shagari was overthrown in the 1983 Nigerian coup d'état and succeeded by Muhammadu Buhari, who was appointed Chairman of a new Supreme Military Council of Nigeria and Commander-in-Chief of the Armed Forces by the junta. Buhari ruled for two years, until 1985, when he was overthrown by General Ibrahim Babangida, who appointed himself with the position of President of the Armed Forces Ruling Council of Nigeria.
Babangida promised a return of democracy when he seized power, but he ruled Nigeria for eight years , when he temporarily handed power to the interim head of state Ernest Shonekan in 1993 in a move towards democratization. Two months later, however, Shonekan was overthrown by General Sani Abacha while Babangida was visiting Egypt.
Abacha appointed himself Chairman of the Provisional Ruling Council of Nigeria. After Abacha's death in 1998, General Abdulsalami Abubakar took over and ruled until Olusẹgun Ọbasanjọ again became head of state (via the 1999 presidential election), ending the junta and establishing the Fourth Nigerian Republic.