President: Goodluck Jonathan
Goodluck Jonathan inherited the presidency in May 2010 on the death of his predecessor, and went on to win elections in April 2011.
International observers gave the 2011 elections their general approval. Other elections since the end of military rule in 1999 have been widely condemned for state-sponsored manipulation.
However, the announcement of the results was followed by violence in the northern stronghold of his main opponent, General Muhammadu Buhari.
The election results revealed a geographical divide, with Mr Jonathan scoring well in the predominantly Christian south, and Gen Buhari sweeping many of the Muslim-dominated northern states.
Mr Jonathan was elected as vice-president to Umaru Yar'Adua in 2007, and had to serve as acting president as Mr Yar'Adua's health declined.
Mr Jonathan has expressed his commitment to fighting corruption. In November 2011, he sacked the head of the country's anti-corruption agency, accusing her of not doing enough to tackle the problem.
The president has since himself been blamed for failing to curb rampant corruption in government and state institutions.
The increasing militancy of the northern-based radical Islamist group Boko Haram has also become a major danger. After a series of bloody attacks on Christmas Day 2011, Mr Jonathan vowed that the government would do all in its power to bring the perpetrators to justice.
Despite this, in 2012 more than 600 people were killed in attacks blamed on Boko Haram, and President Jonathan went on to declare a state of emergency in three northern states and deploy a large number of troops in May 2013.
In 2014 the government faced mounting criticism over his handling of the Boko Haram insurgency, and its reaction to the abduction of more than 200 schoolgirls.
Mr Jonathan was born in 1957 in Bayelsa, a state in the oil-rich Niger Delta. Unlike his predecessor, who was a Muslim from the northern Katsina state, he is a Christian from the south.
After studying zoology at university, he worked as an education inspector, lecturer and environmental protection officer before going into politics in 1998.
Elected deputy governor of his native Bayelsa state in 1999, he was promoted when the governor was impeached on corruption charges in 2005.
Two years later, he was hand-picked to be Mr Yar'Adua's running mate in the 2007 election, which the ticket won amid allegations of widespread vote-rigging.
Mr Jonathan has confirmed he will run again in elections due to take place in February 2015, in the midst of a new offensive by Boko Haram along the shore of Lake Chad.