President: Karolos Papoulias
Born in 1929, veteran Pan Hellenic Socialist Movement (Pasok) foreign minister Karolos Papoulias was elected president by parliament in 2004, and again for a final five-year term in 2010.
The presidency is a largely ceremonial post, as executive power resides with the prime minister, but Greece's debt crisis has thrust President Papoulias into the political foreground as he tries to maintain a stable government in the face of public anger and a divided political class.
Prime Minister: Antonis Samaras
The leader of the conservative New Democracy party since 2009, veteran politician Antonis Samaras formed a coalition government in June 2012 committed to pushing through the austerity package required to secure European Union and IMF funds.
Mr Samaras formed a coalition committed to implementing an unpopular austerity programme
His party won a relative majority at the May general election, but was unable to rally enough support among other parties. A second election in June boosted New Democracy enough to ensure that, in alliance with the Socialist Pasok party and the small Democratic Left, Mr Samaras could become prime minister.
A US-educated economist from a prominent family, Mr Samaras has been a highly contentious figure in New Democracy.
He entered parliament in 1977 and became first finance and then foreign minister under Konstantinos Mitsotakis in 1989.
His hard line over newly-independent Macedonia's use of that name led to his dismissal the following year, and he formed his own short-lived rightwing party. This split New Democracy and brought down the government in 1993.
As the fortunes of his breakaway party waned, Mr Samaras made overtures to New Democracy and rejoined in 2004, become a European MP and then returning to the Greek parliament in 2007.
He won the party leadership five years later, and burnished his divisive reputation by expelling rival Dora Bakogiannis in 2010 over her support for the Pasok government's first EU-IMF bailout deal.
With Greece facing bankruptcy he agreed to support the second bailout and the 2011-2012 governments of national unity, and made his peace with Ms Bakogiannis after the May 2012 election.
Mr Samaras won in June 2012 on a programme of softening some of the terms of the austerity package, such as restoring some pension cuts and directing bailout money to job creation projects.
His government has to a certain extent stabilised the fiscal crisis by pushing through many of the austerity measures required as the price of international bailouts, despite substantial public opposition to spending cuts.
However, there are reports that the need to impose deeply unpopular measures has exacerbated tensions between Mr Samaras and his coalition partners.