Count Hermann Karl von Keyserling (1697–1764) was a Russian diplomat from the Keyserlingk family of Baltic German nobility based in the Duchy of Courland and Semigallia.

Biron was so pleased with the news that he had Keyserlingk appointed President of the Saint Petersburg Academy of Sciences.

A year later, Keyserling was appointed Ambassador of the Russian Empire at the court of August III in Dresden and Warsaw.

His son Heinrich Christian von Keyserling was the wealthiest aristocrat of Königsberg, whose palace was frequented by the likes of Immanuel Kant and Johann Gottfried Herder.

Hermann Karl's daughter Anna von Medem was the great-grandmother of geologist Alexander Keyserling.