Stanisław Saks (30 December 1897 – 23 November 1942) was a Polish mathematician and university tutor, a member of the Lwów School of Mathematics, known primarily for his membership in the Scottish Café circle, an extensive monograph on the theory of integrals, his works on measure theory and the Vitali–Hahn–Saks theorem.

Stanisław Saks was born on 30 December 1897 in Kalisz, Congress Poland, to an assimilated Polish-Jewish family.

[2] In the preface to the English edition, Zygmund writes:[3] Stanislaw Saks was a man of moral as well as physical courage, of rare intelligence and wit.

In the period between the two world wars he exerted great influence upon a whole generation of Polish mathematicians in Warsaw and Lwów.

After the outbreak of World War II and the occupation of Poland by Germany, Saks joined the Polish underground.