(Thread prompted by the one about seeing someone with lizard eyes, who is possessed by a demon)
I have once. Waken from a dead cold sleep, my girlfriend and future wife said to me "we're not alone". I looked at the foot of the bed and their was a very angry young boy. I was shocked and became afraid myself as I sensed a power there, and then, like a balloon popping, he vanished.
She asked me what I saw, I said a very angry young boy, who looked to be age 9-10. She confirmed that was what she saw too.
I suppose it could have been an angry guardian angel, or even a passing demon, but let's go with ghost.
I have never doubted things spiritual since that day. I was about age 19.
I can't say I've had that exact experience.
Start with what quickly became the locus classicus, Imagine Heaven by John Burke, which I'm currently rereading. This covers all kinds of near death experiences. Most are reported upon return, which gives context for visions that do not generally qualify as "near death"; however, it can be categorized as NDE if it's an out-of-body experience (OBE) or an open vision (some of which are reported in process even though the person dies and does not return).
The sentient characters met are of two kinds, those identifiable as humans who lived on earth, and those identifiable as intelligences who appear in service to humans ("angels"). (We should probably include visions of symbols that represent collectives of humans because they act sentient, but these are generally recognized as symbolic and not individual.) Note that there is capacity for deception in this realm, but the fact is that when something tries another tack it can be removed as an outlier. This includes appearances of humans that don't act like they did on earth (deepfakes), appearances of intelligences that don't act like they are there to serve (adversaries), and appearances of sentient cryptids whether or not the cryptid species exists on earth (beasts).
The general rule is that the observer has an intuitive feeling what entity is being dealt with, what is true and what is deceptive, based on the whole experience. That indicates direction but can be trumped by recognition of contradiction later. There are specific exceptions, but reporters generally know by human intuition what they're really dealing with; if they are following a deception they have a consciousness of the contradiction but then face the choice to admit or deny it.
So the "ghost" subset includes both the humans that continue to act as they did and counterfeits that seek to "slide" the human's identity. As pointed out there, the "spirit" subset includes those not clearly identified as earthly humans, and it's common for some light or dark spirits to be seen as a death approaches (here called "reapers" though that is a bit less accurate for their roles of accompaniment and influence). There is evidence that dark spirits can be thwarted in their goals, though I haven't seen evidence that light spirits have been successfully thwarted as they follow natural flow ("letting things happen"). But the spirits as here defined can be distinguished from the ghosts.
The Bible says that the witch of Endor saw the ghost of Samuel and implies that she was shocked because she intended to see a counterfeit instead (a "familiar"). It also says that Stephen saw Jesus as he was dying (though this is a special exception to being a ghost, because Jesus had the body as he said so himself). Christians and skeptics alike experience that the name of Jesus is an unparalleled guide for managing and directing the behavior and communications of all such entities. Therefore the ghost story proper, which categorizes as open vision, can be safely navigated with trust in God to be greater than any ghost; and the allied phenomena give much evidentiary reflection upon the ghost story.