Feodor III of Russia (In Russian: Фёдор III Алексеевич) (June 9, 1661 - May 7, 1682) was the Tsar of all Russia, during whose short reign (1678-82) the Polish influence in the Kremlin was paramount.

Feodor was the eldest surviving son of Tsar Alexius and Maria Miloslavskaya . In 1676 he succeeded his father on the throne. He was endowed with a fine intellect and a noble disposition; he had received an excellent education at the hands of Simeon Polotsky , the most learned Slavonic monk of the day, knew Polish, and even possessed the unusual accomplishment of Latin; but, horribly disfigured and half paralyzed by a mysterious disease, supposed to be scurvy, he had been a hopeless invalid from the day of his birth. He spent most of the time with young nobles, Yazykov and Likhachov, who would later introduce the Russian court to Polish ceremonies, dress, and language.

On July 28, 1680 he married a Ukrainian noblewoman Agatha Gruszewska and assumed the sceptre. His native energy, though crippled, was not crushed by his terrible disabilities; and he soon showed that he was as thorough and devoted a reformer as a man incompetent to lead armies and obliged to issue his orders from his litter, or his bed-chamber, could possibly be. The atmosphere of the court ceased to be oppressive; the light of a new liberalism shone in the highest places; and the severity of the penal laws was considerably mitigated. He founded the academy of sciences in the Zaikonospassky monastery, where everything not expressly forbidden by the Orthodox church, including Slavonic, Greek, Latin and Polish, was to be taught by competent professors.

The chief difference between the Theodorean and the later Petrine reforms was that while the former were primarily, though not exclusively, for the benefit of the church, the latter were primarily for the benefit of the state. The most notable reform of Theodore III, however, was the abolition, at the suggestion of Vasily Galitzine, of "place priority ," which had paralyzed the whole civil and military administration of Muscovy for generations. Henceforth all appointments to the civil and military services were to be determined by merit and the will of the sovereign. Theodore's consort, Agatha, shared his progressive views. She was the first to advocate beard-shaving. On her death (4th of July 1681) Theodore married Martha Apraksina. He died on May 7, 1682, without issue.