Honestly it has only happened once in my life and it was the most petrifying event I have ever experienced. It was about a year ago and my wife and I had yet to move out of our tiny one bedroom apartment. It wasn't a bad neighborhood but we lived in the middle of an urban area. I came home late that night and didn't want to turn the tv on, which is typically how I fall asleep, so I didn't wake my wife. I usually have trouble falling asleep in silence because my mind tends to wander and that night was no exception. Anyway, I remember finally being able to fall asleep after an hour or so of tossing and turning. Now mind you when I say a small one bedroom apartment I mean SMALL; we lived on the top floor of a 2 story home above an elderly woman who barely made a peep during the day never mind at 3 in the morning. The only light in the room at the time came from the light at the corner of our street and it was just enough to cast a shadow along one wall of the room.
I distinctly remember being woken up by the sound of my bedroom creeping open. In my hazy state I looked to my left to see if my wife had gotten up to go to the bathroom or something (or maybe the dog) but she was laying right next to me.
And there it was...
I looked over to my left to see this mammoth of a man, completely dressed in black, shadow across his face, leaning over my sleeping wife. The sheer terror and sweat that brushed over me in that exact moment is really indescribable. As I looked over at this thing leaning over my wife he slowly turned his head towards me and had this humongous teeth baring grin. Honestly the best way to describe this look would be for you to google "evil clown from the Brave Little Toaster."
At this moment I am completely frozen in fear, unable to move, unable to speak, and coming to terms that there is some intruder in my home. I feel something near my feet and realize it is the dog. Now I have a particularly yippy dog when it comes to people entering the house. This was the fact I had to grasp onto to tell myself this wasn't real. "Why didn't the dog bark? No one is here she would have gone crazy." I kept saying that over and over and over to myself and as I kept repeating that the figure slowly dissipated.
I didn't sleep the rest of the night. Pretty sure if it wasn't for the dog a heart attack was in my future.