Major General Theodoros Pangalos (Greek: Θεόδωρος Πάγκαλος) (11 January 1878 – 26 February 1952) was a Greek soldier and politician. A distinguished staff officer and an ardent Venizelist and anti - royalist, Pangalos played a leading role in the September 1922 revolt that deposed King Constantine I and in the establishment of the Second Hellenic Republic. In June 1925 Pangalos staged a bloodless coup, and his assumption of power was recognized by the National Assembly which named him Prime Minister. As a "constitutional dictator" he ruled the country until his overthrow in August 1926. From April 1926 until his deposition, he also occupied the office of President of the Republic.

Pangalos withdrew from public life for a while, but remained active in the Venizelist military circles. During the Axis Occupation of Greece, Pangalos and military officers close to him played a role in the establishment of the Security Battalions and was widely suspected of collaboration with the Germans. Cleared by a postwar court, he ran unsuccessfully for political office and died in 1952.

Pangalos was born on the island of Salamis.His mother was descendant of the local Arvanite fighter of the Greek Revolution, Giannakis Meletis [Hatzimeletis], while his paternal side came from an aristocratic family of Kea island. He graduated first in his class from the Greek Army Academy in 1900 and continued his studies in Paris, France. In 1916 he supported Eleftherios Venizelos in his struggle against King Constantine I, and was rewarded with a senior position in the War Ministry. He participated in the Asia Minor Campaign in senior staff positions, but was demoted after Constantine returned to power in 1920.

In 1922, Pangalos supported the coup d'etat by Nikolaos Plastiras which abolished the monarchy and declared the Second Hellenic Republic, and was made War Minister. His first job was to prosecute a number of prominent pro-monarchist government leaders by military court in what became known as the Trial of the Six, which resulted in six executions; he then rushed to Thessaloniki, from where he successfully reorganized the Greek army in Macedonia and Thrace, as the war with Turkey was not over, and an attack in the region was feared to be imminent. The reorganization was so successful that the Greek High Command prepared for a possible advance into Eastern Thrace in the face of the Turkish demands in the Lausanne peace talks. A sudden reversal of the Turks in April preempted the new war, and the Treaty of Lausanne was signed.

A staunch nationalist, Pangalos objected to the terms of the treaty, and declared that his troops would attack Turkey nonetheless in order to block the deal. He was forced to resign, but his stance made him popular with the many segments of Greek society that objected to the treaty. During the period of political instability that followed, Pangalos jumped into the fray, gaining and losing a number of ministerial positions as governments came and went.

On June 24, 1925, officers loyal to Pangalos, fearing that the political instability was putting the country at risk, overthrew the government in a coup. Pangalos immediately abolished the young republic and began to prosecute anyone who could possibly challenge his authority, including his old chief, Plastiras. Freedom of the press was abolished, and a number of repressive laws were enacted (including a law dictating the length of women's skirts - no more than 30 cm above the ground), while Pangalos awarded himself the Grand Cross of the Order of the Redeemer. Pangalos declared himself dictator on 3 January 1926 and had himself elected president in April 1926. On the economic front Pangalos attempted to devalue the currency by ordering paper notes cut in half. His political and diplomatic inability however became soon apparent. He conceded too many rights to Yugoslav commerce in Thessaloniki, but worst of all, he embroiled Greece in the so-called War of the Stray Dog, harming Greece's already strained international relations.

Soon, many of the officers that had helped him come to power decided that he had to be removed. On 24 August 1926, a counter coup deposed him, and Pavlos Kountouriotis returned as president.

Pangalos was an Albanian speaker, and declared himself proud of his Arvanite heritage. His priority in establishing good relations with Albania was soon materialized by four agreements between the two governments, among others addressing the confiscation of Cham properties before 1926, when Greek refugees from Asia Minor were settled in the region. This agreement stated that Chams would be compensated at least as much as foreign citizens or ethnic Greeks. In a public statement he also recognized that Chams were an ethnic minority and promised that Albanian schools would be opened in the region.

In 1930, Pangalos was sent to prison for a building scandal. He remained in prison for two years and was released during a period when a number of amnesties were given by Venizélos. He never regained the popular support he had before the coup, and never again played a role in Greek politics.

After Greece fell to the Germans in 1941, Pangalos and other Venizelist officers moved to support the new collaborationist regime. He also played an important role, albeit from behind the stage, in the establishment of the Security Battalions, which he hoped to use against both the Communist dominated National Liberation Front and against a possible return of King George II and the royal government from exile. He was accused of collaboration, but was cleared of all charges in September 1945. He unsuccessfully ran for parliament in 1950 and died in Kifissia two years later.

His grandson, also named Theodoros Pangalos, was the Deputy Prime Minister of Greece. He was a member of the PASOK socialist party.

Theodoros Pangalos is mentioned in the song Stin epohi tou Pangalou (In the times of Pangalos, Greek: Στην εποχή του Πάγκαλου) by Giorgos Mitsakis, originally sung by George Dalaras.