Question

What the attempts to stop the holocaust and by whom?

Answer 1

There were many attempts scattered all across Europe to help the Jews escape the Holocaust by many people from sympathetic Germans to scores of others in occupied countries regardless of race, creed, or religion. Within a number of ghettos, a number of resistance efforts by the Jews had also resulted in armed uprisings to defy the Nazis.

Underground networks such as those formed by elements of the French Resistance aided Jews in escaping from Vichy France and other countries.

There's a a lot more detail over at the United States Holocaust Memorial Museum site: http://www.ushmm.org/wlc/en/article.php?ModuleId=10005185