Iraq separates the position of Head of State and Head of Government in two separates roles: the President and Prime Minister respectively.
As of September 19, 2012:
The Head of State is President Jalal Talabani.
The Head of Government (leader) is Prime Minister Nouri Al-Maliki.
The current leader of Grenada is Keith Mitchell
The President, Head of State, and Leader of Armenia is Serzh Azati Sargsyan.
The current (2014) head of state of the Vatican is Pope Francis.
David Cameron is the current UK Prime Minister and Queen Elizabeth II is Head of State.
Fredrik Reinfeldt is the head of Government, while King Carl Gustav XVI(16th) is the head of State.
The current leader of state of the United States is the head of the executive branch. It is President Obama.
Nursultan Abishevich Nazarbayev is the current leader.
Great Britain does not have a leader because it is not a country. The head of state of the United Kingdom is Queen Elizabeth II. The current head of government in the UK is David Cameron.
The current Head of State in Samoa is Tui Atua Tupua Tamasese. After Malietoa Tanumafili II passed in 2007.
The current (28-07-12) leader of government is Prime Minister Donald Tusk. The President, who is the head of State is Bronislaw Komorowski.
Toomas Hendrik Ilves is the president of Estonia, the head of state. Andrus Ansip is the prime minister, the head of government.
Russia has two seats of power that work in tandem, a president and a prime minister. The current prime minister is Vladimir Putin, and head of the government. The current president is Dmitry Medvedev, who is head of state.