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, and one of the founders of the Democrat Party (DP).
Hailing from a landowning family of Western Anatolia, he began his political career in 1930 with the short-lived Liberal Republican Party. After it was banned, he was inducted into the ruling Republican People's Party (CHP), identifying with the party's liberal-conservative faction that was against land reform and national enterprises. With the Motion with Four Signatures incident and internal party opposition to President İsmet İnönü, he was expelled from the CHP in 1945, and cofounded the center-right Democrat Party with Celâl Bayar, Mehmet Fuad Köprülü, and Refik Koraltan.
The DP came to power after winning the 1950 general election, which represented a peaceful transition of power from the CHP. Bayar was subsequently elected president, and tasked Menderes as DP leader and prime minister from 1950–1960. Menderes relaxed restrictions on religion. His premiership saw Turkey's economy initially boom with Marshall Plan aid and privatization, until the economy stalled in the mid-50s. During his premiership, Turkey participated in the Korean War and was admitted to NATO in 1952. Menderes' government was controversial for entrenching an authoritarian regime, using state resources to harass the opposition, particularly the CHP and İsmet İnönü; suppressing the press, and initiating the Istanbul Pogrom.
Menderes was overthrown in the 1960 coup d'état. He put on trial for corruption and violating the constitution. He was convicted with the death penalty and hanged along with two other cabinet members: Fatin Rüştü Zorlu and Hasan Polatkan. He was the last Turkish political leader to be executed after a military coup. In 1990, the Turkish parliament passed a law rehabilitating Menderes, Polatkan, and Zorlu. He is 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.