Jean-Louis Koszul (French: [kɔsyl]; 3 January 1921 – 12 January 2018) was a French mathematician, best known for studying geometry and discovering the Koszul complex.

Koszul was educated at the Lycée Fustel-de-Coulanges [fr] in Strasbourg before studying at the Faculty of Science University of Strasbourg and the Faculty of Science of the University of Paris.

His Ph.D. thesis, titled Homologie et cohomologie des algèbres de Lie, was written in 1950 under the direction of Henri Cartan.

Koszul married Denise Reyss-Brion on 17 July 1948.

He died on 12 January 2018, at the age of 97, nine days after his 97th birthday.