I realize that the list was theoretically based solely on the number of kills, so it did not include Vasily Zaitsev, but they might have mentioned him, given that he had 225 kills in just in a two-month period at the end of 1942, achieving a rate that approached (but could not equal) the per diem of “The White Death”. You may have heard about Zeitsev from the book Enemy at the Gates, and the film based on that book, which featured Jude Law as Zeitsev.
(Enemy at the Gates is an embellished account of Zeitsev’s service in Stalingrad. Many say that his duel with a German sniper was entirely a fiction created by Soviet propaganda. The fact of that embellishment does not mean that Zeitsev was not accomplished. His real achievements were almost equally impressive.)
Since WW2, the greatest has been Abdorrasul Zarrin, now considered by many to be the greatest sniper in history, with as many as 3,000 kills. An Iranian sniper in the Iran–Iraq War, he had more than 700 confirmed kills during that war alone.