overman vs taskmaster

overman

noun
  • A person who supervises others; a supervisor, especially in a mine. 

  • A person with great powers; a superman. 

verb
  • To provide with too many personnel; overstaff. 

taskmaster

noun
  • Someone who supervises workers, especially one who imposes hard or burdensome work. 

  • A source of hard work or responsibility. 

How often have the words overman and taskmaster occurred in a corpus of books? (source: Google Ngram Viewer )