Georgios Papandreou (Greek: Γεώργιος Παπανδρέου, Geórgios Papandréou; 13 February 1888 – 1 November 1968) was a Greek politician, the founder of the Papandreou political dynasty. He served three terms as the prime minister of Greece (1944–1945, 1963, 1964–1965). He was also deputy prime minister from 1950 to 1952, in the governments of Nikolaos Plastiras and Sofoklis Venizelos. He served numerous times as a cabinet minister, starting in 1923, in a political career that spanned more than five decades.

After studying law in Athens and political science in Berlin, Papandreou enlisted as a volunteer in the First Balkan War. He first run for political office in the 1920 national elections and was a principal member of the 11 September 1922 Revolution that overthrew King Constantine I. Thereafter, he became a prominent Liberal politician, surviving an assassination attempt in 1921 and being imprisoned by Theodoros Pangalos's dictatorship in 1925. After having briefly attained ministerial experience at the start of the Second Republic, Eleftherios Venizelos elevated him to the ministries of Education and Transport in 1930 and 1933 respectively, overseeing the construction of over three thousand schools amidst the Greek refugee crisis. He was again arrested and exiled in 1938 by the 4th of August Regime, remaining in exile for four years.

Imprisoned by Italian forces in World War II during the Axis Occupation of Greece, he agreed to head the Greek government–in–exile in 1944. As German forces evacuated Greece in October 1944, Papandreou became the first post–occupation prime minister, heading a unity government and overseeing the suppression of communist EAM forces in Athens in the Dekemvriana. He resigned in early January 1945 and rose to becoming deputy leader of the Liberal Party under Sofoklis Venizelos. He would deputise both Venizelos and Nikolaos Plastiras as deputy prime minister before the Liberals lost the 1952 elections, resulting in the former relinquishing the party leadership to Papandreou. Despite winning the popular vote, the short–lived Democratic Union failed to win the 1956 elections. The merger of the Liberal Party and other parties in 1961 created the Centre Union that Papandreou led in that year's elections. Incumbent Konstantinos Karamanlis won the election, but Papandreou alleged fraud in the results, proclaiming a "relentless struggle" against the incumbent government.

The Centre Union won a minority vote in the 1963 elections and formed a government in the 1964 elections. On his return as head of government, he led economic liberalization efforts and wealth redistribution policies amidst the Greek economic miracle, increased mandatory years in education and enforced free education on all levels. In foreign policy, he assumed a pro–Enosis stance amidst clashes in Cyprus, and was increasingly advised by his son, Andreas Papandreou.

His relationship with the new King, Constantine II, was deteriorating, and following the refusal of Minister of National Defence Petros Garoufalias to vacate his position regarding the ASPIDA scandal in the army, Papandreou openly clashed with the King and resigned in July 1965. The latter lured in Centre Union members to form unelected coalition governments, resulting in prolonged political instability for the next two years. Papandreou denounced the "Apostates" of the Centre Union and declared a second "struggle", together with his son, Andreas. Before the 1967 elections could commence, a coup d'etat in April 1967 saw the installation of a military regime and the arrest of both Papandreous. Georgios was placed under house arrest and died in November 1968.

Papandreou was known as the "Old Man of Democracy" by his supporters. He established a political dynasty, that most prominently included his son Andreas, who would later serve as prime minister from 1981 to 1989 and 1993 to 1996, and grandson George, who served as prime minister from 2009 to 2011.

Papandreou was born Georgios Stavropoulos at Kalentzi, in the Achaea region of the northern Peloponnese. He was the son of Father Andreas Stavropoulos, an Orthodox archpriest (protopresvyteros). His last name is derived from his father's Christian name and the word papas "priest". He studied law in Athens and political science in Berlin. His political philosophy was heavily influenced by German social democracy. As a result, he was adamantly opposed to the monarchy and supported generous social policies, but he was also extremely anti-communist (and specifically against the KKE's policies in Greece). As a young man, he became involved in politics as a supporter of the Liberal leader Eleftherios Venizelos, who made him governor of Chios after the Balkan Wars. One of his brothers, Nikos, was killed in the Battle of Kilkis-Lachanas.

He married twice. His first wife was Sofia Mineyko, a Polish national, daughter of Zygmunt Mineyko and paternal granddaughter of Stanislaw Mineyko (1802–1857). Their son Andreas Papandreou was born in Chios in 1919. His second wife was the actress Cybele Andrianou and their son was named George Papandreou.