Here is some of what /u/commiespaceinvader has written/said about Hitler as an agent of history:

• What is the consensus on the "Weak Dictator" theory of Hitler and the cause of the Holocaust? (lots of good English-language sources in this response)
• Would you say that Hitler was necessary for WWII?
• When did hitler go crazy?
• Did Hitler know about the Holocaust?
• To what extent do you guys think Hitler was personally responsible for the Holocaust?
• AskHistorians Podcast Episode 57: Intentionalism and Functionalism in the Holocaust
• Did Hitler ever personally witness any of his atrocities?
• Hitler and 'Great Man Theory'

See also What was Hitler's stake in the Holocaust? answered by a now-anonymous redditor

From /u/Georgy_K_Zhukov:

• On why there is stuff we don't know Hitler's opinion about, and also, it isn't that interesting...

• Hitler's lack of friends

• Hitler's military service in WWI

( Transcript of AskHistorians Podcast #57 )