Horloogiyn Choybalsan (1895–January 26, 1952) was the Communist leader of Mongolia from the 1930s until his death. The spelling of his name can vary greatly; "Horloogiin", "Horloyn", "Khorloyn", and "Khorloogiyn" are sometimes used instead of Horloogiyn, and "Choibalsan" is a common alternative to Choybalsan. He served both as head of state (Chairman of the Presidium of the State Little Hural, 1929 - 1930) and head of government (Chairman of the Council of People's Commissars, 1939 - 1952) and dominated the country's political world. He is sometimes accorded the military rank of Marshal.

Choybalsan was a close follower of the Soviet leader Joseph Stalin and emulated his policies in many ways. Choybalsan rose to power with Soviet backing, given as the result of Stalin's displeasure with Mongolian communist leader Peljidiyn Genden. Genden had, among other things, scaled back the implementation of a command economy, refused permission for Soviet troops to be based in Mongolia, and refused an order from Stalin to "liquidate" Buddhist monks. When Stalin increased the pressure on Mongolia, Genden accused Stalin of imperialism. In 1936, Genden was removed from power, and he was shortly thereafter arrested and killed. Choybalsan, who was willing to follow Stalin's orders without question, gained power.

Choybalsan's rule is generally regarded as being the most tyrannical to have occurred in recent Mongolian history. Under Choybalsan, many purges of "enemies of the people" were conducted. These focused on religious figures, the former aristocracy, and on political dissidents. Estimates of the number of people killed vary considerably, but are generally substantial. Choybalsan was also the centre of large personality cult modeled on that of Stalin. On the other hand, during his rule considerable improvements in the country's infrastructure, roads and communication lines were made with Soviet assistance, and steps were taken toward improving the country's literacy rate.

Choybalsan held the position of Prime Minister until his death on January 26, 1952. His image in modern Mongolia is mixed: many people still consider him to be a Mongolian hero, but his critics claim that this is merely the result of his propaganda and personality cult. Some Mongolians believe that Choybalsan was merely a puppet of Stalin, and had little choice in his actions. For its part, Choybalsan's party, the Mongolian People's Revolutionary Party, criticized him for committing "errors", including the establishment of the personality cult, in 1956. Today, it acknowledges that Choybalsan was a tyrant, but claims that it was just as much victimised by him as were other Mongolians — many party members, particularly followers of Genden, were purged during his rule.