Hafizullah Amin (Pashto/Dari: حفيظ الله امين;‎ 1 August 1929 – 27 December 1979) was an Afghan communist revolutionary, politician and teacher. He organized the Saur Revolution of 1978 and co-founded the Democratic Republic of Afghanistan (DRA), ruling Afghanistan as General Secretary of the People's Democratic Party from September 1979 until his assassination in December 1979.

Born in the town of Paghman in Kabul Province, Amin studied at Kabul University and started his career as a teacher before he twice went to the United States to study. During this time, Amin became attracted to Marxism and became involved in radical student movements at the University of Wisconsin. Upon his return to Afghanistan, he used his teaching position to spread socialist ideologies to students, and he later joined the People's Democratic Party of Afghanistan (PDPA), a new far-left organization co-founded by Nur Muhammad Taraki and Babrak Karmal. He ran as a candidate in the 1965 parliamentary election but failed to secure a seat, but in 1969 became the only Khalqist elected to parliament, increasing his standing within the party.

Amin was the main organizer of the April 1978 Saur Revolution, which overthrew the government of Mohammad Daoud Khan and formed a pro-Soviet state based on socialist ideals. Being second in chief of the Democratic Republic, Amin soon became the regime's strongman, the main architect of the state's programs including mass persecution of those deemed counter-revolutionary. A growing personal struggle with General Secretary Taraki eventually led to Amin wrestling power away then successfully deposing him and later ordering his execution; on 16 September 1979, Amin named himself Chairman of the Council of Ministers (head of government), Chairman of the Revolutionary Council (head of state), and General Secretary of the PDPA Central Committee (supreme leader).

Amin's short-lived leadership featured controversies from beginning to end. His government failed to solve the problem of the population revolting against the regime as the situation rapidly worsened and army desertions and defections continued. He tried to change things with friendly overtures to Pakistan and the United States, and considered a trade-off of recognizing the Durand Line border in exchange for Pakistan halting support to anti-regime guerillas. Many Afghans held Amin responsible for the regime's harshest measures, such as ordering thousands of executions. Thousands of people disappeared without trace during his time in office. The Soviet Union under Leonid Brezhnev was dissatisfied with and mistrusted Amin; they intervened in Afghanistan, invoking the 1978 Twenty-Year Treaty of Friendship between Afghanistan and the Soviet Union. Soviet operatives assassinated Amin at the Tajbeg Palace on 27 December 1979 as part of Operation Storm-333, kickstarting the 10-year Soviet–Afghan War; he had ruled for slightly longer than three months.