Szmul Zygielbojm was a Polish Jewish socialist politician, Bund trade-union activist, and member of the National Council of the Polish government-in-exile.
Zygielbojm was born in 1895 to a working-class family and had to leave school at age ten. In his early twenties he became involved in Bund trade-union activism, and in 1924 was elected to the Bund Central Committee. He edited a Bund newspaper and in 1938 was elected to the Łódź city council. Upon Germany's invasion of Poland, he fled to Warsaw and was briefly a member of the Judenrat.
He fled to the Netherlands, then to England, where he was appointed to the National Council of the Polish government-in-exile. He interviewed Jan Karski and tried to publicize the mass murder of Jews in German-occupied Poland. After the Warsaw Ghetto Uprising was brutally crushed, and Warsaw's remaining Jews murdered by units under SS-Brigadeführer Jürgen Stroop, Zygielbojm committed suicide to protest the inaction of the western Allies.