Here is one: 'I stared at the mirror. A face that wasn't mine stared back.' Well, this kind of story creates a sense of horror in just two sentences. The first sentence sets the scene, like in a normal situation. And then the second sentence suddenly brings in the abnormal or scary element. It plays on our fear of the unknown. For example, in the mirror story, seeing a face that isn't yours is a very creepy concept. It makes you wonder what could be causing it, is it a ghost or some sort of supernatural entity? It quickly grabs your attention and makes your skin crawl.
Sure. 'The old house was silent. Then I heard a child's laughter from the attic.'
One could be 'The door creaked open. A shadowy figure with no face stared at me.'
I woke in the night to a cold hand on my face. When I turned on the light, there was no one.
The old house was silent. Then I heard a child's laughter from an empty room and no one was there.
Well, '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.' And also 'The cemetery was empty. But as I passed by, I heard whispers coming from the graves.'
One: The old house was silent. Then I heard a child's laughter echoing from the attic.
Here's another: 'She walked down the empty alley. A shadowy figure began to follow her silently.'
Some other scary two - sentence stories could be. 'The cemetery at midnight was still. But then the tombstones started to tremble.' 'I was alone in the old library. Suddenly, a book flew off the shelf and landed at my feet.'
Here is another one. 'She opened the old book. A pressed flower fell out.'
Sure. Here are two: 'I told my wife she was drawing her eyebrows too high. She looked surprised.' Another one is 'I saw a sign that said 'Watch for children'. I thought, that sounds like a fair trade.'
In the mirror, a face that wasn't mine stared back. It grinned as I screamed.