When I was around 13, I moved into in a relatively large house in a small neighborhood. My room was on the second story, and I had a window that was almost completely hidden by the high headboard of my bed. I say almost completely hidden, because about a quarter of it could be seen above the headboard.
I was and still am really paranoid about people watching me, so I would feel uncomfortable at night while on my computer, even though it seemed impossible for someone to look into a window several feet off the ground. Whenever the thought would come into my head, I would take the pillows from my bed and put them on the top of the headboard to cover the window.
After a few months of living there, I would sometimes hear tapping. It was as if someone was knocking on wood. At first it was one or two knocks, but after a while it would be three or four knocks. It didn't happen very often, but it always happened late at night. I told my father, the only other person that lived in the house, but he would always dismiss it as the cat. After enough convincing, I decided that it was probably the cat.
After a year passed, with the tapping happening every other day or so, my cat passed away. It was sad, because I had her since she was just a kitten, and her passing was very unexpected. She was an indoor cat, and somehow managed to get outside. We thought she had just ran away at first, but after a week of searching we found her. She had been killed by what we assumed was a dog or other wildlife creature.
I didn't hear the tapping after my cat died, so that comforted me in that I knew it was indeed her who was doing it, or so I thought. After around a month, I heard the tapping again. This time, it wasn't the sound of wood. It was the sound of someone tapping on a window. I was facing the computer, and facing away from the almost-covered window, so hearing that tapping and hearing it so clearly, I didn't really know what to do. I ran out of my room and told my dad, he came into my room and looked out the window to find nothing. I couldn't sleep for the rest of the night, or rather I wouldn't sleep.
We moved a few weeks later due to my father being promoted and needing to move closer to his work. The worst part about the whole thing, is that I recently found out that the people that moved into our house after us were murdered in the house during the night. Their killer was apparently an old neighbor that broke into their room via the window. According to my father, who was relaying this news to me, the killer's house had several pictures of our house inside it, the pictures dated back to around 2006, when we still lived in the house.