Congradulations, you probably have Sleep Paralysis just like me. And also Mary Shelley, which is pretty cool.
It's a condition that 75% of people will experience but <2% will have recurring episodes of.
SP is like the opposite of sleep walking - when sleep walking, your brain has trouble shutting off the body while you sleep, but in SP your brain paralyzes your body too soon before sleep or forgets to restart it once you wake up. Since your brain is in sleep mode, it also turns on the little part that creates dreams which creates hypogognic hallucinations, what you have been seeing. They seem real because your dreams are generally realistic and your mind is blending both your perception of the actual world around you and the fake things it is generating.
I generally use it to transition to lucid dreaming - being fully aware of the fact that you are in a dream and being able to control it - since I can fall asleep without 'falling asleep' if you understand that.
I do see similar things - shadowy figures around my bed, I hear people coming out of my closet and feel them sit on my bed behind me, things like that. A little creepy, but if you remember that it's just you mind, you can keep calm.
It's harmless, but if you want it to stop, I'm sure your doctor can help.