The White Death

 

Simo Hayha served as a sniper for Finland when they were defending against the Soviet Union during WW2. 

While other snipers were reportedly shot and detected easily for peeking out when using their rifle, Hayha upgraded his rifle with an iron sight for better efficiency.
He was also known for putting snow in his mouth to prevent the frosty breath from giving his position away. 
Although he was shot in the face and critically wounded on one day, he was saved by his comrades and was comatose till a day after the war ended or so.