User blog comment:GravityMan/Literature vs History 8: Golden Ticket Extravaganza/@comment-25872721-20160306064558/@comment-25872721-20160311033903

Not sure what the hint is from so I'll just analyse the image name.

DIRTY HARRY HINT:

Dirty Harry's final film is called "The Dead Pool"

According to Wikipedia, Dirty Harry (film) is based off the Zodiac Killer case.

GUESSES:

Deadpool/Deathstroke or Zodiac are my guesses, though I think both are wrong.