His work is grotesque and nightmarish, and feels profoundly Freudian (lots of scary vaginas). One the war started he pretty much became a recluse, and remained one for the rest of his life, holing up in a 12th century castle in Austria. His work was declared "degenerate" and "decadent" by the Nazis (if one wishes to be strictly truthful, he was both. The question is really whether you have a problem with it or not), but they pretty much left him alone. Unsurprisingly, he illustrated work by Poe, E.T.A. Hoffman and Dostoyevsky.
He also wrote a couple of strange dystopian novels, all of which are sadly out of print in English (unless you have a Kindle!). It's all terribly evocative. I decided to feature him here because I found that once I started looking at his pictures, I simply could not get them out of my head. I haven't read his famous novel, The Other Side, but I've heard very good things. One wonders what went on in his mind as he worked alone in his castle. One looks at his work and shudders.