Baron, Graf[b] Hans Heinrich von[c] Fersen or Ivan Yevstafyevich Fersen (Russian: Иван Евстафьевич Ферзен, romanized: Ivan Yevstaf'yevič Ferzen) was a Russian military commander and general of the infantry from the nobility of what was then Russia's Livonia.

[2] In 1790 he acted in Finland against the Swedes, where he assisted Vasily Chichagov's ships in the Bay of Vyborg with the fire of coastal artillery batteries, increasing the confusion of the Swedish warships in the bay.

[2] In 1792, in the aftermath of the adoption of the constitution of 3 May 1791 he formed in Lithuania a general confederation (after the example of Targowica), which was enacted under the patronage of Empress Catherine II, and thus quickly pacified the whole region.

[1] Fersen gained notoriety with the defeat and capture of Kościuszko in the battle of Maciejowice.

In 1797 he was appointed director of the First Cadet Corps; he soon retired and died in his Livonian estate.