This happened to my brother when I was about 8 years old. My brother was 24 years old at the time. He worked as security in an office building all night long.
Before I get into the story, I'll describe the setting. We had a lot of cats. It started with one cat, and then strays moved in, they multiplied, and we ended up with more than ten cats. The place where we lived was a duplex with a garage that we turned into a house in the back, and a big yard in between. At night, the cats were a problem because they would make a ruckus.
My brother would sleep during the day and wake up around 10pm, when pretty much everybody in the household was asleep. Our bathroom had the sink next to a window looking out toward the yard. As my brother was going through his bathroom routine, he feels that something is watching him. He thought it was nothing and just a figment of his imagination... Until he looked outside.
He saw a cat that was looking at him while sitting on top of one of his cars. He looked at it and he said that what struck him was that its eyes were glowing red. Again it didn't concern him much because he figured that it was just the reflection that cat eyes normally give. He stared at it a bit more and then it's when it happened. He says that as the cat stared back at him, a second head leaned out of the first one and then a third one, all with the same glowing red eyes. It then looked away and jumped off the car.
It's safe to say that it freaked him out. He went and woke up my parents and my oldest sister and they went outside to see if they could see it. They could not find it. Here's the weird part, out of all the cats we had, not one cat was in our backyard. It was as if we had no cats.
He hasn't seen anything like it before or since but he is convinced that it was a demon cat. (if such a thing exists) My brother isn't the type to make things up and the fact that he went to get my parents makes me believe he did see something that night. He went to work that night but nothing happened. He says that he felt that the air was heavy where he worked but that was it. Any thoughts?