Simon Dubnow (alternatively spelled Dubnov, Russian: Семён Маркович Дубнов, Semyon Markovich Dubnov; Yiddish: שמעון דובנאָװ, Shimen Dubnov; 10 September 1860 – 8 December 1941) was a Jewish historian, writer and activist. He is the father-in-law of Henryk Erlich, a famous Bundist leader.