white hat vs white knight

white hat

noun
  • A good person; a hero. 

  • A well-meaning hacker who hacks for a good cause or to aid a company, organization, or government without causing harm. 

  • A sailor. 

white knight

noun
  • A hero, savior, or righteous individual. 

  • An individual or corporation that intends to acquire another company in order to avert a hostile takeover. 

  • Someone who unnecessarily defends someone else. 

  • A man who defends a woman in debate etc. in an attempt to gain her favour. 

  • A mushroom of species Tricholoma album. 

verb
  • To unnecessarily defend someone, especially in an attempt to gain favour. 

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