This happened to me, personally, when I was about 10 years old and it's something that I put in the back of my mind until recently because of a similar situation with my little sister. I woke up around 1:00am in my grandparent's home, where I lived at the time. There were no lights on in the room I was in, no night-light, no closet lights, etc. But there appeared to be some kind of shadow of a dog that was running in place on the wall in front of me. The figure of the dog reminded me of a German Shepherd or Wolf kind of dog.
As soon as I saw it, I was instantly terrified. I jumped out of the bed to go get my grandmother to see if she could somehow explain the shadow. But as I got out of bed, the fear intensified greatly which made me break out in a full run and as I got further from my room I felt like there was something chasing me. Once I hit my grandmother's room, the fear and the feeling of being chased disappeared.
When I tell people this story I always get the chills and goosebumps, even as I type this right now. I am Native American, and in my culture we strongly believe in spirit animals and guardian animals and to this day, this is the only time that I have ever been scared of a Wolf-like creature. They are usually very calming to me.
This experience only ever happened once and it has always been very confusing for me to understand. Does anyone have any idea what this could have been and why it could have happened? Even after tons of research, I can't find anything that could explain it.