Count Frans David Alopaeus (also Alopeus) (December 19, 1769 in Vyborg - June 13, 1831 in Berlin) was an Imperial Russian diplomat.
Born into the Finnish noble Alopaeus family, he followed his older brother Maximilian von Alopaeus into a diplomatic career. He was enrolled at the Military Academy in Stuttgart from 1781 to 1785. He studied at the Georg-August-Universität in Göttingen. He was the Imperial Russian ambassador to Stockholm from 1803, and took part in the negotiations for the Peace of Fredrickshamn in 1809. He was granted a title of Count along with the coat of arms in 1820 in Congress Poland for his negotiations on Congress Poland's borders with Kingdom of Prussia.