That's my first thought when someone posted that "killswitch" thread last week.

They come for you when you die. Those who have had near death experiences, when they were ahem bad people, have spoken about it. I had a relative who said as much. Same as witnesses to the deaths of other, ah, not so good folks. They shouted about demons or "this isn't right, something is not right" sort of things at their end. It's not a warm pleasant tunnel of light kinda thing for everyone.

Could be hallucinations, but those who've looked into the scientific literature on dear death experiences like I have, there is something more there, even if we can't fully quantify it.

My first thought. Some kind of invisible entity.