Count Carl Gustaf Mannerheim (10 August 1797 – 9 October 1854) was a Finnish nobleman, amateur entomologist and governor of the Viipuri province in the Grand Duchy of Finland.

From 1835 he served as the chief judge of the newly formed Imperial Court of Appeals (“Kayserlichen Hofgerichtes”, hovioikeus) in Vyborg.

Mannerheim devoted much of his time to natural sciences and acquired a significant scientific collection of Coleoptera.

Through a network of aristocratic collectors across Finland, Sweden and Russia, he amassed a collection of 100,000 specimens representing 20,000 species over a 4-decade period.

He also collaborated with other zoologists including Fredrik Wilhelm Mäklin, Viktor I. Motschulsky, and Edouard Ménétriés.