One more is 'The photograph on the wall changed. It showed me dead.' This is extremely creepy as it involves a familiar object, a photograph, changing in a very disturbing way. It makes you feel like there is some kind of premonition or supernatural force at work.
Another scary one is 'I heard whispers in the basement. I live alone.' The isolation combined with the unexplained whispers in a normally unoccupied part of the house is really spooky. It makes you wonder what could be making those noises. Is it a ghost? A malevolent spirit? Or something else entirely? This short story leaves a lot to the imagination which is what makes it so frightening.
A story about a doll that moves on its own at night. The owner would wake up to find the doll in different positions every morning. One night, she heard the doll giggling and saw its eyes following her around the room. It was terrifying.
One story could be 'I woke up to find a handprint on my window. It was on the inside.'
One of the scariest stories could be about haunted houses. Maybe a family moved into an old house and started experiencing strange noises at night. Doors would open and close by themselves, and cold drafts would sweep through the rooms even when all the windows were closed.
One story could be 'I heard a knock on the door at midnight. When I opened it, no one was there but I felt a cold hand on my shoulder.'
A good one is 'I woke up to see a figure at the foot of my bed. It disappeared when I turned on the light.'
Another really scary one could be 'My phone rang at 3 am. The caller ID said it was me.' It plays on the idea of the self being something other or unknown, and calls at that time are always spooky.
I think 'The clock stopped at midnight. Then I heard footsteps.' is quite scary. It gives this feeling of something ominous starting right at a spooky time.
I think 'I heard a child crying in the basement. But I live alone.' is quite terrifying. The idea of a crying child in a place where no child should be, especially when you live alone, plays on our fears of the unknown and the supernatural. It makes you wonder what could be down there, and the thought that it's not a normal, explainable situation is very frightening.
My phone rang in the middle of the night. It was my number calling me.
In some, it's the sudden appearance or disappearance. For example, 'She was walking in the empty hallway. A figure emerged from the wall and vanished.' The unexpected emergence and then quick vanishing is really scary.