Fyodor Alexeyevich Semyonov, born on April 20 (May 1) 1794 in Kursk, Russian Empire, and died there on April 18 (30), 1860, was a Russian amateur astronomer. He came from a merchant family and taught himself mathematics, astronomy, physics, and chemistry. After his father's death, Semyonov used his inheritance to purchase a small estate, where he dedicated himself to scientific pursuits. He independently created a refractor with a focal length of 180 cm and regularly observed celestial bodies, paying special attention to solar and lunar eclipses. In 1842, together with Moscow professor D. M. Perevoshchikov, he observed a solar eclipse.

In 1856, Semyonov published the work "Tables of Time Readings of Lunar and Solar Eclipses from 1840 to 2001 on the Moscow Meridian in the Old Style," where he presented the calculated elements of 243 lunar and 172 solar eclipses visible in the Northern Hemisphere. He performed all calculations independently. For this work, Semyonov was awarded the Gold Medal of the Russian Geographical Society.

Soviet astronomer A. A. Mikhailov noted that Semyonov's work is remarkable for the volume of work done without computational assistance. Despite lacking formal education and being in a provincial merchant environment, Semyonov was able to study theoretical astronomy and compile a canon of eclipses that preceded the work of Western European specialists by decades.

Semyonov was an honorary citizen of Kursk.