Seriously, if time travel was possible, Hitler's life would be a running gun battle among time travelers who wanted to prevent WW II and the Holocaust and those who believe that the ripples of killing some half skilled Austrian painter had horrible effects in the future for some reason. Toss in a few Illinois Nazis who want to rescue him from 1945 Berlin and you probably would have to park your time machine blocks from him because of all the people who got there before you.
Maybe, but I think Hitler would have to take a back seat to Stalin and Mao with respect to all those who want to take them out before their mass murder sprees. When it comes to genocide, Hitler was a piker compared to Stalin and Mao.