Poll: Who do you think was the greatest atheist of the twentieth century ?

If you are asking who was the most accomplished person who is known to be an atheist, that would have been either Josef Stalin or Mao Tse-Tung. Magnitude does not imply righteousness. If you are asking who was most accomplished at representing atheists, Madeline Murray O'Hare takes the prize easily. There may have been great people who are not widely known to be atheists.