Kazimierz Sakowicz (1894–1944) was a Polish journalist, soldier and member of the Polish resistance against Nazism. A witness to the prolonged Ponary massacre in German-occupied Vilnius, he chronicled much of it in his diary, before being murdered in 1944.
His diary was published several decades after his death under the title Ponary Diary (first, in Polish in 1999, and translated into English in 2005). It is a detailed record of that atrocity of the Second World War, in which about 100,000 Jews, Poles and Russians were murdered by Germans and Lithuanian collaborators.