Ali Adnan Ertekin Menderes (Turkish: [adˈnan ˈmændeɾes]; 1899 – 17 September 1961) was a Turkish politician who served as Prime Minister of Turkey between 1950 and 1960. He was one of the founders of the Democrat Party (DP) in 1946, the fourth legal opposition party of Turkey. He was tried and hanged under the military junta after the 1960 coup d'état, along with two other cabinet members, Fatin Rüştü Zorlu and Hasan Polatkan. During his tenure, Turkey participated in the Korean War, and was admitted to NATO in 1952. He was the last Turkish political leader to be executed after a military coup. He is also one of the four political leaders of the Turkish Republic who have been honored with a mausoleum, the others being Kemal Atatürk, Süleyman Demirel, and Turgut Özal.

Adnan Menderes was born in 1899 in Koçarlı, Aydın, as a son of a wealthy landowner of Crimean Tatar origin. After primary school, Menderes attended the American College in İzmir. He fought against the invading Greek army during the Turkish War of Independence and was awarded a medal of honour. He graduated from the Ankara University Law School. In 1930, Adnan Menderes organized a branch of the short-lived Liberal Republican Party (Turkish: Serbest Cumhuriyet Fırkası) in Aydın. After the party dissolved itself, he was invited by Atatürk himself to join the ruling Republican People's Party and was selected by the party leaders as a deputy of Aydın in 1931. In 1945, he was expelled from the party with two other colleagues due to inner-party opposition to the nationalization policies of İsmet İnönü.

In June 1945, Menderes, together with Celâl Bayar, Fuat Köprülü and Refik Koraltan demanded more political and democratic freedom in their Motion with four signatures. The motion was not approved by any member of the Turkish parliament except for the four who brought the motion to parliament, and by September 1945, Menderes, Köprülü and Koraltan were all stripped of their membership of the CHP due to their opposition to the Turkish government. Bayar then resigned from parliament and later also the party. On 7 January 1946, the four formed the Democratic Party (DP) and in the 1946 elections Menderes was elected deputy of the Democratic Party representing Kütahya.

When the DP won 52% of the votes in the first free elections in Turkish history on 14 May 1950 in which votes were cast in secret and counted openly, Menderes became prime minister, and in 1955 he also assumed the duties of foreign minister. He later won two more free elections, one in 1954 and the other in 1957.

During the 10 years of his term as prime minister, the Turkish economy was growing at a rate of 9% per annum. He supported an eventual military alliance with the Western Bloc and during his tenure, Turkey participated in the Korean War, and was admitted to the NATO in 1952 with the support of the opposition Republican People’s Party (CHP). With the economic support of the United States via the Marshall Plan, agriculture was mechanized; and transport, energy, education, health care, insurance and banking progressed. Some historical studies note that Turkey experienced a significant economic downturn in the mid-1950s during Prime Minister Adnan Menderes’s tenure, including an estimated 11% decline in GDP per capita in 1954.

In 1955, several historical sources link the Menderes government to the Istanbul pogrom, which targeted the city's Greek ethnic minority. In September 1955 a bomb exploded close to the Turkish consulate in Greece's second-largest city, Thessaloniki, also damaging the Atatürk Museum, site of Atatürk's birthplace. The damage to the house was minimal, with some broken windows. In retaliation, in Istanbul thousands of shops, houses, churches and even graves belonging to members of the ethnic Greek minority were destroyed within a few hours, over a dozen people were killed and many more injured.

The ongoing struggle between Turkey and Greece over control of Cyprus, and Cypriot intercommunal violence, formed part of the backdrop to the pogrom. The United Kingdom invited Turkey and Greece to a conference in London, which started on 26 August 1955. The day before the Tripartite London Conference (29 August – 7 September 1955) began, Menderes claimed that Greek Cypriots were planning a massacre of Turkish Cypriots. Seeing the opportunity to extricate Britain, Prime Minister Anthony Eden advised the Turkish delegates that they should be stern. Foreign Minister Fatin Rüştü Zorlu paid heed to Eden and launched a harsh opening salvo, stating that Turkey would reconsider its commitment to the Treaty of Lausanne unless Greece reconsidered its position on Cyprus. The Greek delegates, surprised by the harshness of the speech, held the British responsible for the change in Turkish attitudes. Finally, the conference fell apart on 6 September, the first day the subject of Cyprus would be broached at the conference, when news broke of the bombing in Thessaloniki.

Deflecting domestic attention to Cyprus was politically convenient for the Menderes government, which was suffering from an ailing economy. Although a minority, the Greek population played a prominent role in Istanbul's business life, making them a convenient scapegoat during the economic crisis in the mid-1950s. The DP responded first with inflationary policies, then when that failed, with authoritarianism and populism. DP's policies also introduced rural-urban mobility, which exposed some of the rural population to the lifestyles of the urban minorities. The three chief destinations were the largest three cities: Istanbul, Ankara, and İzmir. Between 1945 and 1955, the population of Istanbul increased from 1 million to about 1.6 million. Many of these new residents found themselves in shanty towns (Turkish: gecekondus), and constituted a prime target for populist policies.