Born September 9, 1922 in the village of Apiranthos (or Aperathu), Naxos, Glezos moved to Athens in 1935 together with his family, where he finished high school. During his high school years in Athens he also worked as a pharmacy employee. In 1939 he created an anti-fascist youth group against the Italian occupation of the Dodecanese and the dictatorship of Ioannis Metaxas.
He was admitted to the Higher School of Economic and Commercial Studies in 1940. At the onset of the WWII, he asked to join the Greek army in the Albanian front, but he was rejected because he was under age. Instead, he worked as a volunteer for the Hellenic Ministry of Economics.
On May 30, 1941, he and Apostolos Santas tore down the Swastika flying from the Acropolis. Their act inspired the Greeks to resist against the occupation, and established them both as two of the most respected WWII veterans. The Nazi regime responded by sentencing Glezos and Santas to death in absentia.
Glezos was arrested by the German occupation forces on March 24, 1942, and he was subjected to imprisonment and torture. As a result of this treatment, he was gravely affected by tuberculosis. He was arrested on April 21, 1943 by the Italian occupation forces and spent three months in jail. In February 7, 1944 he was arrested again, this time by Greek Nazi collaborators. He spent another seven and a half months in jail, until he finally escaped on September 21 of the same year.
However, the end of the war was not the end of Glezos' plight. On March 3, 1948 he was put to trial for his political convictions and sentenced to death multiple times. However, his death sentences were not executed, because of the public outcry. His death penalties were reduced to a life sentence in 1950.
Even though he was still imprisoned, Manolis Glezos was elected member of the Hellenic Parliament in 1951, under the flag of the United Democratic Left (EDA). Upon his election, he went on a hunger strike demanding the release of his fellow EDA MPs that were imprisoned or exiled in the Greek islands. He ended his hunger strike upon the release of 7 MPs from their exile. He was released from prison on July 16, 1954.
On December 5, 1958 he was arrested and convicted for espionage, which was common pretext for the persecution of the supporters of the left during the Cold War. His release on December 15, 1962 was a result of the public outcry in Greece and abroad. During his second term of post-war political imprisonment, Glezos was reelected MP with EDA in 1961.
At the coup d'etat of April 21, 1967, Glezos was arrested at 2am, together with the rest of the political leaders. During the Regime of the Colonels, the military dictatorship led by George Papadopoulos, he suffered yet another four years of imprisonment and exile until his release in 1971.
The aftermath of Manolis Glezos' political persecution, from WWII to the Greek Civil War and the Regime of the Colonels is 11 years and 4 months of imprisonment, and 4 years and 6 months of exile.
For a long time Manolis Glezos withdrew from mainstream politics, except for an unsuccessful attempt to revive EDA (in which he was secretary until 1985 and president from 1985 until 1989), in order to focus on the community of Aperathu and try to implement a local grassroots democracy experiment. He ran for president of the community council, and he was elected by a landslide. Then, he essentially abolished the privileges of the council, introducing a "constitution" and establishing a local assembly that had total control over the community administration. This model worked for several years, but in the long term the interest of the rest of his community wore off and the assembly was abandoned.
In the consecutive legislative elections of 1981 and 1985, Glezos was elected a member of the Hellenic Parliament, this time with the Panhellenic Socialist Movement. In 1984 he became a member of the European Parliament.
In the 2000 Greek legislative election he led the state MP ticket of the Synaspismos party of the radical left. In 2002, he formed the political group called Active Citizens, and he ran as a candidate prefect for Attica achieving 10.79%. The Active Citizens are part of Coalition of the Radical Left, an alliance with Synaspismos (in English Coalition) and other minor parties of the Greek left, which took part in the 2004 Greek legislative election.
Manolis Glezos was awarded the Lenin Peace Prize in 1963. He was pronounced honorary Doctor of Philosophy of the University of Patras in 1996, of the Aristotle University of Thessaloniki in 2001, and of the National Technical University of Athens in 2003.
Apart from his political work, Glezos invented a system to prevent floods, combat erosion and preserve underground water, that works by collecting rain water inside wells in order to direct it to aquifers. He also frequently wrote articles in Greek newspapers and published four books in Greek:
- "The history of book" («Η ιστορία του βιβλιού», 1974);
- "From dictatorship to Democracy" («Από τη δικτατορία στη ∆ηµοκρατία», 1974);
- "The phenomenon of alienation in the language" («Το φαινόµενο της αλλοτρίωσης στη γλώσσα», 1977);
- "The conscience of the rocky earth", («Η συνείδηση της πετραίας γης», 1997).