Florian Marciniak codename: Jerzy Nowak, Nowak, J.Krzemień, Szary, Flo (born May 4, 1915 in Gorzyce - Died February 20/21 1944 in Gross-Rosen) was a Polish Scoutmaster (harcmistrz), first Naczelnik of the Szare Szeregi (Scouting resistance) during the Second World War. He was also the graduate of St. John Cantius High School in Poznań.

Marciniak was arrested by the Gestapo on May 6, 1943 and murdered on February 20/21 1944 in the German concentration camp Gross-Rosen.