The frightening experience I am going to share with you isn't mine, it's my grandma's (mom's mother) story. My grandma was the coolest lady I have ever seen. I loved her so much and whenever I used to visit her she told me a different story every night. Once, when I was sleeping with her, she talked about her experience at the previous house she lived with my grandpa. (I never saw my grandpa as he died of brain tumor when my mom was very young.)
The incident goes like this. My grandpa and grandma were sleeping at the terrace of the house as it was a hot summer night and there was some electricity problem at the house. They got this house on rent for some time and one floor of that place was locked.
As my grandma explained, my grandpa was a cleanliness freak. That night she woke up with the noise of falling water. She thought that my grandpa was doing it while he was sleeping right beside her and she didn't notice. She went to the bathroom and saw the back of a man, thinking it was my grandpa, she yelled at him saying, "This isn't the time for cleaning, why don't you sleep and let me sleep too?" The guy turned back towards my grandma but his face wasn't visible. Grandma went close to him and he suddenly grabbed her hand. She screamed at once as the man had fangs (vampire like teeth) and his eyes were black. My grandpa came there at once as he heard grandma's scream and the entity disappeared. After that, nobody slept at the terrace.
Later the owner of the house told them that a Brahma-Rakshasa (Brahma-Rakshasa is the spirit of a dead Brahmin who has done evil things in his life) lives there and the floor is locked because of that. He also told them that the house was very old. Although even he didn't had any idea about the reason of the presence of that devil in his house.
My grandma also discovered that, she was pregnant and according to Hindu ideology if a lady is pregnant, they are prone to get attacked by negative entities. My grandma also heard from the neighbors that a man died here. She left the house in a month and everything was normal after that.
While my grandma was telling me about the incident, I was able to see that fear in her eyes and I know it wasn't just a story.