Alright, let's get started...
In my dreams, I have confronted a fair few monstrosities. Some of them are humanoid, some of them are partially invisible, and some are just completely unrecognizable. These ones involve me stalking them, or them stalking me, or an out-and-out fight/chase. In many cases, the absurdity of it draws me to the conclusion that I'm dreaming and that the mere denial of the reality prevents any actual harm. I'm a lucid dreamer, you see. In other cases, I'm dealing with them using equally-ridiculous options, like firing away with a handgun made literally out of my hand. (Yes, it really happened.)
Of course, these are nothing compared to the deja vu dreams. My reality has been compromised by these damn things. Yes, I'm a lucid dreamer, but it takes me a little while to catch on. Still, though... After I get up, eat breakfast, get ready to go out, get up, eat breakfast, get ready to go out, get up, eat breakfast, and get ready to go out...over and over again...it doesn't take a super-genius to realize that his body hasn't moved an inch! So, I have to suspect reality because my dreamtime imagination is pretty good at fabricating it.