Markovian Parallax Denigrate is a series of unexplained word puzzles posted to the discussion system Usenet in 1996. No one knew what to make of them. Between the CIA machination scenario and the simple spam, an important list of potential solutions to that puzzle were given.

In the position of “The Thinker” by Auguste Rodin facing this unsolved mystery, THD is trying to figure out the meaning of that message.

It is often considered as the first Internet mystery.