Alexander Papannastasiou (1876-1936) was a thinker and politician who emerged as one of the leading political figures in Greece's political life in the 20th century. He studied law and social sciences in Athens and philosophy in Heidelberg.

In 1907, he participated in founding the "Sociological Society" as an organization of young scientists, aimed at producing studies for the modernization of Greek society and addressing the needs of the people.

In 1910, he entered the political arena, was elected as a Member of Parliament, and led the fight for the expropriation of the Thessalian landownings and their redistribution to small farmers and landless peasants. He participated in establishing the "Educational Club" in 1910, aiming to reform the educational system and establish teaching in the demotic language.

He fought as a volunteer in the Balkan Wars, joined Venizelos's liberal party, which expressed the bourgeois modernization of the country and a strong irredentist nationalism. He participated in the National Defence Movement in 1916 and became a leader of the radical democratic camp.

He was elected as a Member of Parliament multiple times, served as Minister of Transport, Interior, and Welfare in Venizelos's governments, and was twice Prime Minister. In 1922, he published the "Democratic Manifesto," condemning the disastrous policies of pro-royalist governments during the Asia Minor campaign, which led to his imprisonment.

In 1923, he founded the "Democratic Union" party and the daily newspaper "Democracy," of which he was the main columnist. In 1926, the party was renamed the "Worker-Peasant Party." In 1924, as Prime Minister, he was the founder of the non-monarchical Democracy in Greece (Second Greek Democracy), established with the historic resolution of March 25 by the Fourth Constituent Assembly, which the Greek people approved through a referendum on April 13.