Simo Häyhä, often referred to by his nickname, The White Death, was a Finnish military sniper during World War II in the 1939–1940 Winter War between Finland and the Soviet Union. He used a Finnish-produced M/28-30 rifle and a Suomi KP/-31 submachine gun. Häyhä is believed to have eliminated over 500 enemy soldiers during the conflict, the highest number of sniper kills in any major war. Consequently, he is often regarded as the deadliest sniper in history.

A sniper is a military/paramilitary marksman who engages targets from positions of concealment or at distances exceeding the target's detection capabilities. Snipers generally have specialized training and are equipped with telescopic sights. Modern snipers use high-precision rifles and high-magnification optics. They often also serve as scouts/observers feeding tactical information back to their units or command headquarters.