We had a lovely Persian/Angora mix cat named "Boo". She got her name from the way she'd arch her back and hop sideways if something startled her. She was with us for right around 22 years before her kidneys failed.
About 2 weeks after we lost her, I was walking into the living room of the condo my wife and I lived in, and I happened to look over at my recliner. Boo loved to nestle into the top portion of the recliner, where the cushion meets the back. It was a heavy recliner, and there's now way the wind could move it. The chair began rocking as if Boo had jumped down from her favourite perch. We had not yet gotten any cats to fill the heartaching void left by her passing. This happened on more occassions that I can count.
We ended up getting a 2 more cats to dispel the crushing silence of our home. We soon found that Selena and Caleb were playing and romping with the "thin air", as if another cat were in the house. We quickly learned that Boo was still very much with us.
3 years ago, we moved to a new house. Selena and Caleb settled in quite nicely, but they would wander about the house in the middle of the night, crying, as if calling to another cat. We knew what was going on. They missed Boo.
We went back to the condo to complete the cleanup so the new owner could take posession. We were overcome with a feeling of loneliness as we went about our work. So, that night, we invited Boo to come with us to our new home. We used everything we know to entice and encourage her spirit, and it worked.
And follow us, she did. She's taken up residence in the lower two floors of the house, and all three of our cats know she's there and play with her. It's really odd to see a cat wrestle with "nothing", rolling around on the floor as if there are indeed two cats at play. And the same recliner moves even thought it's not been touched.
So, yes. My house is haunted by a very happy little ghost cat named Boo.