Frederik Herman Henri (Frits) Kortlandt (born June 19, 1946, Utrecht) is a professor of descriptive and comparative linguistics at Leiden University in the Netherlands.
He writes on Baltic and Slavic languages, the Indo-European languages in general, and Proto-Indo-European, though he has also published studies of languages in other language families.
He has also studied ways to associate language families into super-groups such as Indo-Uralic.