Idriss Deby came to power in a coup and has faced several attempts to oust him by similar means.
He won a fourth term in presidential elections in April 2011, which the main opposition parties boycotted as they did the 2006 elections.
He survived a bid to topple him in April 2006, when rebels attacked the capital, and again in February 2008, when they were beaten back by government forces backed by French warplanes and troops offering logistics, intelligence and protection.
In May 2013 the government said it had foiled another coup plot, this time allegedly involving army officers and an opposition MP.
Idriss Deby was born in Fada, in north-east Chad, in 1952. A career army officer, he helped Hissen Habre topple Goukouki Oueddei in 1982.
In 1989 he fled to Sudan after being accused of plotting a coup. A year later his Patriotic Salvation Movement drove Mr Habre into exile and in 1991 Mr Deby was proclaimed president.
He won Chad's first post-independence presidential election in 1996 after overseeing the introduction of a multi-party constitution. He was re-elected in 2001, and in 2005 won a referendum allowing him to stand for a third term.
An Amnesty International report in 2013 accused Mr Deby of brutally repressing critics of his rule, and of ignoring promises to respect human rights when he came to power in 1990.
Mr Deby has actively intervened in the affairs of neighbouring countries, His troops have been present in the Central African Republic and Mali, and he courted controversy in January 2012 when he married the daughter of Musa Hilal, the alleged leader of the feared Sudanese Janjaweed militia.