Florian Marciniak (codenames: Jerzy Nowak, Nowak, J.Krzemień, Szary, Flo; born 4 May 1915, Gorzyce, Kościan County – died 20/21 February 1944, Gross-Rosen) was a Polish scoutmaster (harcmistrz), and the first Naczelnik (Chief Scout) of the paramilitary scouting resistance organization, the Szare Szeregi, during the Second World War. Marciniak was a graduate of St. John Cantius High School in Poznań. He was arrested by the Gestapo on 6 May 1943 and murdered in February 1944 at the Gross-Rosen concentration camp.