Dmitry Sergeevich Chelkak (Дмитрий Сергеевич Челкак; born January 1979 in Leningrad) is a Russian American mathematician.

[1] His research deals with conformal invariance of two-dimensional lattice models at criticality, specifically the Ising models of statistical mechanics, in which he showed universality and conformal invariance at criticality with the Fields medalist Stanislav Smirnov.

[1] In 1995 he received the gold medal at the International Mathematical Olympiad.

In 2004 he was awarded the "Young Mathematician" Prize of the St. Petersburg Mathematical Society.

[1] In 2018 was an invited speaker at the International Congress of Mathematicians in Rio de Janeiro with talk Planar Ising model at criticality: state-of-the-art and perspectives.