I have seen and heard a number in my time, animal ghosts also, a ghost cat which I've written about at this forum before.
The one which stands out to me was the first that I saw and it happened in 1979.
My parents divorced when I was 8 and my mother met another man some years later. In 1979, we moved two hours south of Sydney to large property in the Southern Highlands of New South Wales, Australia.
The house we lived in was built by the son of the founder of Sydney's first newspaper and was (and still is) what could be termed a grand mansion. It was a 'u' shaped house, had 16 bedrooms, 49 rooms in total, a separate ballroom (we used as a billiard room), plus there were two other houses on the property, one by the gate (which I've written about here also) and the stable keepers house.
One portion of the house was two stories high and also contains two large cellars. This section of the house was previously the staff quarters and in comparison to the rest of the house, was rather dilapidated.
For me, who'd grown up in the city, I found this part fascinating. There was lots of junk left from the previous owners (a doctor and his family) plus my step father's collection of stuff that his mother had collected on the journeys around the world.
One afternoon after school, I was upstairs exploring through boxes of books and old photos when I needed to go to the bathroom.
The only bathroom upstairs had a toilet which faced directly away from the door. When exiting the room, you then looked directly toward the landing of the staircase that you walked up to get there and a large window looking out into the paddocks/fields outside.
After finishing and washing my hands, I walked out to continue my explorations when I saw a man with his back towards me, on the landing looking out the window.
He was quite a purple colour and though someone had drawn his outline in thin air. The outline however, was fuzzy and seemed electric, insomuch as it appeared to be moving. He had his arms behind his back and appeared to be wearing a military uniform. I could see epaulets on his shoulders, although he had no hat on.
I stared at him, unable to move, terrified for some seconds, at least 10, if not more. He was blocking my only way downstairs. The figure continued looking out the window as it slowly faded away before me eyes.
I stayed where I was and took a step closer, only 2 metres from where it stood and waiting a few more moments before running down the stairs to tell my mother.
She didn't disbelieve me, though told me not to be frightened. A year or so later, she had her own experience, seeing a lady in a dressing gown walk out of an open bedroom door, down a hallway and into another bedroom late one night.
As mentioned, I've seen a number since, but this was my first and most memorable.