Marc Krasner (1912 – 13 May 1985, in Paris) was a Russian-born French mathematician, who worked on algebraic number theory.
Krasner emigrated from the Soviet Union to France and received in 1935 his PhD from the University of Paris under Jacques Hadamard with thesis Sur la théorie de la ramification des idéaux de corps non-galoisiens de nombres algébriques.
In 1944 he introduced the concept of ultrametric spaces,[2] to which p-adic numbers belong.
In 1951, alongside Lev Kaluznin, he proved the Krasner-Kaloujnine universal embedding theorem, which states that every extension of one group by another is isomorphic to a subgroup of the wreath product.
In 1958 he received the Prix Paul Doistau–Émile Blutet of the Académie des Sciences.