The Finnish Democratic Republic (Finnish: Suomen Kansanvaltainen Tasavalta) was a short-lived Communist regime in those minor parts of Finland that were occupied by the Soviet Union during the Winter War. Its government was known under the name of the Terijoki Government. The Soviet Union argued that it was the only rightful government for all of Finland that was capable of ending the Winter War and restoring peace.

It was established on December 1, 1939, in the then-Finnish town of Terijoki (which is now Zelenogorsk in the Leningrad Oblast of Russia). During its lifespan its Otto Ville Kuusinen was chairman and head of government.

On March 12, 1940, it was merged with the Karelian ASSR within the Russian SFSR to form the Karelo-Finnish SSR, a Soviet republic in its own right.