Adolf Hitler was one of the sole reasons for the holocaust. But, the main person who organized the death camps, directed them, and oversaw the "final solution" was Heinrich Himmler. Adolf was a figure head and the brains, along with other people. He influenced a whole country to follow him because of his speaking abilities and peoples hatred of the jews after WW1.
Although he made the holocaust, Hitler also achieved getting a whole country out of a german great depression. He bounced the country back from the ruins of WW1 and he improved the economy so much that the unemployment rate was below 10%. He was a great man in the terms of a politician but a terrible one as well.