Mark Twain 
The Mysterious Stranger, And Other Stories 

The Mysterious Stranger is a novel attempted by the American author Mark Twain. He worked on it intermittently from 1897 through 1908. Twain wrote multiple versions of the story; each involves a supernatural character called "Satan" or "No. 44". All the versions remained unfinished (with the debatable exception of the last one, No. 44, the Mysterious Stranger).