My mother told me this story from when I was very young. I have no memory of it myself. My parents are sensible people, not easily frightened.
For several nights in a row, I would wake up in our old house, crying and terrified. My parents would run to my room to calm me down. I would tell them, through my tears, that a dark shape was standing in the corner.
They thought it was just a bad dream, or perhaps the family dog casting a strange shadow. Then, one evening, my mother came to check on me. She paused in the hallway, looking through the slightly open door.
She saw a tall, shadowy figure leaning over my bed. The moment she pushed the door open to rush inside, the shape was gone. It simply vanished.
After that night, my sleep was peaceful again. The thing never returned. My mother still says she has no explanation for what she saw.