Simo Häyhä. The current holder of the worlds most confirmed sniper-kills in any major war.
505... and that's only sniper-kills.
With his SMG that number increases to 705 and with unconfirmed kills his record rises above 900.
His killing-spree lasted 100 days
It was during the Winter War (1939?1940), between Finland and the Soviet Union.
His killing-spree lasted 100 days, killing soviet soldiers and counter-snipers sent out specifically to kill him, earning him the name "The White Death" among the soviets.
When he wasn't busy slaughtering soldiers, he spent his time dodging tanks and artillery-strikes, showering the area in hopes to get rid of him, one of which, tore holes in his jacket but leaving him unharmed.
His spree was finally ended March 6 1940, where he was shot in the head.
Not that it stopped him... He died peacefully of old age in 2002.