I have quite a few of these and I think I did some of them last year around Halloween, but will tell the 'full body apparition' one again as it was by far, the most scary thing.
When I was a child, my mother died. A year or two later, the person who was going to marry my dad and become stepmother, and her kids, came to stay with us prior to dad re-marrying. The house couldn't fit everyone in, unless Dad slept downstairs on the sofa, and I shared his big double bed with the girl my age, who was about to be my step-sister.
These people were utter strangers to me (Dad was marrying a childhood sweetheart we'd never met, from the other end of the country). The little girl my age was perfectly nice but she and I didn't have a thing in common. So we weren't about to confide in eachother.
I know this was the week it happened as it was the only time we slept in what had been my parents' bedrooom.
The house was an 18thC farmhouse, with 19thC bits and the whoe back end had been knocked down and rebuilt in the 50s. This was the 70s. So this bedroom was in the new bit of the house, and not 'spooky' in any way.
I should add, my brother's room and mine were in the 19thC part of the house and were badly 'haunted' Our whole childhoods, some afternoons we'd hear this old man's voice, screaming obscenities and abuse. We had neighbours but no men, let alone old men, and in any case the walls were 3 foot thick. So we had no idea where this voice came from. It was in the house - not out in the street. Weird as it sounds, we got used to it. We never experienced this anywhere but his room or mine.
Anyway, these people staying were strangers so we didn't tell them about the house being 'haunted' in any case I think it had gone quiet for a long while, by then. So they weren't primed for thinking of the house as spooky. It had a huge rep in our village, and had for decades, as 'the haunted house'. But these were outsiders and didn't know a thing.
One night, that week, my future stepsister was asleep and I was still wide awake. I became aware of a man floating in the air, about a metre away from me. He looked like he was sitting on a chair. He was transparent - made up of pinprinks of coloured light. But he was very much there. He was doing something I couldn't see, and intent on it (like fixing something). So he wasn't looking up. He was on my side of the bed and was elderly, with a white beard and wearing what I'd now think of as 19thC farm labourer clothes.
I know I was paralysed with fear, just as other people describe. Then something kicked in and I quickly turned to face the other side (where stepsister was) but in my hurry to turn away, and not being used to dad's bed which had a metal headboard, I banged my head hard on the bed's head. I was glad of this after as I realised, if I had been asleep or imagining it, I would have 'woken up'. And known it was a dream. Next morning, to confirm, I had a whacking bruise on my forehead.
Over the years I tried to laugh it off. Odd thing was, I only told my dad - a cynic in all things - and he strangely believed me. In later years he swore he never had a single paranormal experience there and he lived in that house from 1954-mid 1990s. I never told the other little girl and slept there the rest of the week, no doubt cacking myself. I never slept in that room again.
Anyway. I go about my life and as years go on, tell my future husband all about it.
15 years later, I meet up for a meal with stepsister. At some point in the evening, she launches into this story about once, that week we shared a bed, when I was fast asleep... she saw the ghost of an old man, hovering in the air, about a metre from the bed.... And goes on to describe, word for word, what she saw.
She told her mum at the time, like I told dad - but both of us swore them to secrecy as we didn't want these strangers to find out in case they thought we were nuts!
My husband almost fainted as she told the story as he had heard it so many times, from me.
When she got to the end I told her I had seen it too.
She went on to tell me that years later, there were other houseguests including her boyfriend who was present with us now, and others from the stepfamily - and they were awoken at 2AM by a very abusive old man at the front door, battering at it and screaming obscenities. It was so loud people of two different floors of the house were woken by it. My dad slept through.
In the morning, the people who'd heard it compared experiences and couldn't believe someone down the street hadn't called the police.
As I posted before, around the early 2000s I went back to the village and saw at the library an exhibition of Victorian photos of the village. And there was one of the top of our lane- when our old house was still a farmhouse. Standing outside it - an old man with a white beard. I nearly shat myself.