But seriously folks...
I can't narrow it down to one person. Like DaveTWB, I have candidates.
Hitler. If we're talking sheer influence over the lives of billions, Hitler's at the top. His actions shaped just about every aspect of post-war politics and allowed for a deeper understanding of World War I and its effects.
Freud. Despite being dead for over 60 years, his theories of development, sexuality, and personality continue to influence psychological theory.
Einstein. E=mc2. Need I say more?
FDR. He employed Socialism to save Capitalism.
The Beatles. Tough to give them the nod over Elivs, but since they wrote their own songs, I have to. Popular culture has a "before" and "after" point, and that fulcrum is the Beatles.
Babe Ruth. The most enduring sports figure of the 20th Century.
Gandhi. Civil disobedience
MLK. Civil rights.
Mother Teresa. The enduring face of 20th Century altruism.
I can probably think of others equally deserving...
