Orest Danilovich Khvolson or Chwolson (Russian: Орест Данилович Хвольсон) (November 22 (N.S. December 4), 1852 – May 11, 1934) was a Russian and later Soviet physicist and honorary member of the Soviet Academy of Sciences (1920). He is most noted for being one of the first to study the gravitational lens effect.[1]