Kazimierz Kuratowski (b. February 2, 1896, d. June 18, 1980) was a Polish mathematician who worked primarily in general topology and mathematical logic.

He is probably best known for a celebrated theorem in graph theory: that a graph $G$ is planar iff neither the complete graph $K_5$ on $5$ vertices nor the complete bipartite graph $K_{3, 3}$ on a pair of $3$-element sets appear as edge subdivisions of subgraphs of $G$ (closely related to Wagner’s theorem that this is the case iff neither $K_5$ nor $K_{3, 3}$ appear as graph minors of $G$).