Samuel Kanyon Doe (May 6, 1950/1951–September 9, 1990) was the president of the West African country of Liberia from 1980 to 1990. His regime was characterized by ethnically-based dictatorship and the suppression of political opposition.

Doe's portrait from the 50 dollar Liberian bill.

Trained by the American Green Berets, Doe was an ethnic Krahn, part of a rural and deprived tribe in inland Liberia. The Krahn were part of the large majority of the Liberian population that was of native African descent, which had long been repressed by the Americo-Liberian elite, who were descended from the freed slaves-turned-colonists from America who founded Liberia in 1847.

On April 12, 1980, Doe staged a military coup, killing President William R. Tolbert, Jr. in his palace and establishing a military regime (the People's Redemption Council) with himself at its head. This marked the first time since Liberia's establishment as a nation that the country was governed by people of native African descent, and the early days of the regime were marked by mass executions of members of Tolbert's deposed government. In August 1981, Thomas Weh Syen , who opposed moves by Doe that were perceived as pro-American, was arrested along with four other members of the People's Redemption Council for allegedly plotting to assassinate Doe; the alleged conspirators were executed a few days later.

During his first years in office, Doe quickly developed an affinity with the U.S. government, especially during the administration of Ronald Reagan. He openly supported U.S. Cold War foreign policy in Africa during the 1980s, and once even challenged diplomats to a fistfight when they criticized the U.S. in his presence. He developed his political and speechmaking skills by watching Reagan's speeches on television.

Doe had a new constitution approved by referendum in 1984 and went on to win a presidential election on October 15, 1985, officially taking 51% of the vote, although suspicions that the vote was rigged were widespread. It is also thought that Doe changed his official birthdate from 1951 to 1950 in order to meet the new constitution's requirement that the president be at least 35 years old. Thomas Quiwonkpa , who had been a leader of the 1980 coup along with Doe, attempted to seize power on November 12; the attempt failed after fighting in Monrovia and Quiwonkpa was killed. Doe was formally sworn in on January 6, 1986.

Under Doe, Liberian ports were opened to American, Canadian, and European ships, which brought in considerable foreign investment from foreign shipping firms and earned Liberia a reputation as a tax haven.

In the late 1980s, as fiscal austerity took hold in the United States and the threat of Communism declined with the waning of the Cold War, the U.S. began cutting off critical foreign aid to Doe. This combined with the popular anger generated by Doe's favoritism toward his native Krahn tribe placed him in a very precarious position.

Charles Taylor, an former ally of Doe's, crossed into Liberia from Côte d'Ivoire on December 24, 1989 to fight a guerrilla war against him. Taylor had broken out of a United States jail after Doe had accused him of embezzlement. By mid-1990, most of Liberia was controlled by rebel factions. Doe was captured in Monrovia by faction leader Prince Johnson on September 9, 1990 and killed shortly thereafter; his brutal execution was filmed and the videotape was widely circulated.