Girija Prasad Koirala, commonly known as G. P. Koirala(Nepali: गिरिजा प्रसाद कोइराला, born 1925), is a Nepalese politician and the President of the Nepali Congress, a major political party. He has been Prime Minister of Nepal four times, serving from 1991 to 1994, 1998 to 1999, 2000 to 2001, and from 2006 to 2008; he was also Acting Head of State from January 2007 to July 2008. He has been active in politics for over sixty years and is a pioneer of the Nepalese labour movement, having started a labor movement in the Jute mills of his hometown Biratnagar. In 1991 he became the first democratically elected Prime Minister since 1959, when his brother B. P. Koirala and the Nepali Congress party swept the country's first democratic election. In an interview with the privately owned Kantipur Television of Nepal, Mr Koirala admitted to printing fake Indian currencies to run political campaigns while being in exile in India around 1971. 

In Nepal's first multi-party democratic election in 1991, Koirala was elected as a Member of Parliament from the Morang-1 and Sunsari-5 constituencies. The Nepali Congress won 110 of the 205 seats in the Pratinidhi Sabha, the lower house of parliament. He was subsequently elected as the leader of the Nepali Congress parliamentary party and was appointed as Prime Minister by King Birendra.

During his first term, the house of representatives enacted legislation to liberalize education, media and health sectors in the country. The government also founded the Purwanchal University and the BP Koirala Institute of Health and Sciences (BPKIHS) in the Eastern Development region and granted licenses to private sector to run medical and engineering colleges in various parts of the country. The government also undertook the construction of the BP Memorial Cancer hospital in Bharatpur, Nepal with assistance from the government of China.

In November 1994 he called for a dissolution of parliament and general elections after a procedural defeat on the floor of the House when 36 Members of Parliament (MPs) of his party went against a government-sponsored vote of confidence. This led to the Communist Party of Nepal (Unified Marxist Leninist)-led coalition coming to power in the elections that followed.

Koirala took over as Prime Minister from Surya Bahadur Thapa following the collapse of the coalition government led by Thapa. Koirala first headed a Nepali Congress minority government until December 25, 1998 after which he headed a three-party coalition government with the Communist Party of Nepal (UML) and the Nepal Sadhbhawana Party.

Koirala became Prime Minister in 2000 for his third term following the resignation of Krishna Prasad Bhattarai, under whose leadership party had won the parliamentary election. The Nepali Congress Party had won the election claiming Krishna Prasad Bhattarai would be the Prime Minister, but Koirala led a group of dissident MPs and forced Bhattarai to resign or face a no confidence motion. At that time Nepal was fighting a civil war against the Communist Party of Nepal (Maoist). During his third term as Prime Minister, his government was plagued by allegations of corruption. Following the massacre in the Royal Palace, Koirala was further criticized for his perceived inability to handle the crisis. Koirala resigned in July 2001 following which the military was mobilized in the civil war for the first time, something Koirala had unsuccessfully attempted to do while in office. He was replaced by former Prime Minister Sher Bahadur Deuba, who was elected by majority of members of Nepali Congress.

After the reinstatement of the Nepal House of Representatives, Pratinidhi Sabha, on 24 April 2006 following the Loktantra Andolan, Koirala was selected to become Prime Minister by the leaders of the Seven Party Alliance.

The reinstated House of Representatives passed laws to strip the King of his powers and bring the Army under civilian control.

Following the promulgation of the interim constitution, Koirala, as the Prime Minister, has been the interim head of state of Nepal.

On 1 April 2007, Koirala was re-elected as Prime Minister to head a new government composed of the SPA and the CPN (Maoist).

Following the April 2008 Constituent Assembly election, the Constituent Assembly voted to declare Nepal a republic on 28 May 2008. Koirala, speaking to the Constituent Assembly shortly before the vote, said that "we have a big responsibility now"; he said that Nepal was entering a "new era" and that "the nation's dream has come true".

In the discussions on power-sharing that followed the declaration of a republic, the Nepali Congress proposed that Koirala become the first President of Nepal; however, the CPN (Maoist), which had emerged as the strongest party in the Constituent Assembly election, opposed this. At a meeting of the Constituent Assembly on June 26, 2008, Koirala announced his resignation, although it would not be finalized until after the election of a President, to whom the resignation had to be submitted.

Koirala was present for the swearing in of Ram Baran Yadav, the first President of Nepal, on July 23, 2008. He submitted his resignation to Yadav later on the same day. CPN (M) ChairmanPrachanda was elected by the Constituent Assembly to succeed Koirala on August 15, 2008, and Koirala congratulated Prachanda on this occasion.

Currently, Mr. Koirala is leading a democratic front composed of parties that support and promote liberal democratic principles and aspire for a lasting establishment of democratic form of governance in Nepal. Mr. Koirala wrote a book Simple Convictions: My Struggle for Peace and Democracy