One of best selling German authors, with 200 millions books sold worldwide and yet, practically unknown in English speaking world.
I will quote Wikipedia http://en.wikipedia.org/wiki/Karl_May
Karl May was a popular German writer, noted mainly for adventure novels set in the American Old West, (best known for the characters of Winnetou and Old Shatterhand) and similar books set in the Orient and Middle East (with Kara Ben Nemsi and Hadschi Halef Omar). In addition, he wrote stories set in his native Germany, in China and in South America.
I grew up reading his books. His Winnetou, the Red Gentleman - the Apache chieftain and his German friend Old Shatterhand are deeply ingrained in the culture here in Europe. The actor that played the main character in the movie is big celebrity here even after 30 years.
I was absolutely shocked when I found out that many of his books have not been translated into English and that even his most famous books have only very recently been translated.
Please note, that Karl May has never seen the "Wild West" or "Orient", so many of things he wrote are ... aehm ... amusingly naive.