At various times, and from various parts of the world, there have been convincing reports of crimes and of assaults on people - and sometimes on animals - for which there is no generally acceptable solution. The cases described in the following list are in no particular order, as they are all just as intriguing and incredulous as each other. Many of these have no definable perpetrators, but these are all crimes that have been carried out in the most curious and perplexing of circumstances that truly defy all sense of logic and meaning.