Mieczysław Niedziałkowski (September 19, 1893 in Vilnius - June 21, 1940 in Palmiry) was a Polish politician and writer.

He took part in the defence of Warsaw in 1939 against the Nazi German aggression, organizing the volunteer militias.

He was subsequently arrested and interrogated by the German secret police or Gestapo.

He was shot dead on 21 June 1940 in Palmiry during the German AB-Aktion.

Niedziałkowski was personally interviewed by Heinrich Himmler, who asked "What do you want from us; what do you expect?"