Andrzej Grzegorczyk [ˈandʐɛj ɡʐɛˈɡɔrt͡ʂɨk] (born August 22, 1922, Warsaw, Commonwealth of Poland) is a Polish mathematician. He is known for his work in computability, logic, and the foundations of mathematics (Krajewski and Woleński, 2008). Grzegorczyk was the first to describe the Grzegorczyk hierarchy, a subrecursive hierarchy that foreshadowed computational complexity theory.