This event took place in the early to mid-1980's. While not really very frightening it's my only experience with what was probably a ghost.
I shared an old farmhouse, located between Silverdale and Poulsbo in Washington State, with three roomates: John, his girlfriend Sharon, and Ken. We were all around 25 or so. The place used to be a small dairy farm owned by Ken's grandparents. They'd built the place and lived there most of their adult lives. In fact, Ken's grandpa had died there. His grandma was still living in a nearby nursing home.
I awoke one Saturday morning between 9:00 and 9:30. I threw on some clothes and went across the hall to the bathroom (This all took place upstairs). I looked out of the window to see if Ken or Sharon's cars were there, intending to see if they were home and might want to join me in finding something to do that day. I knew that John was at work and wouldn't return until Monday evening as he was a paramedic in a nearby town's fire department and on a 72 hour shift. I saw that Ken's and Sharon's cars were both gone. Sharon always took her dog with her and I saw her cat walking across the back yard. I was completely alone in the house. All this just took a few seconds. I was still doing my business when I heard footsteps climbing the stairs, coming down the hall (the one really squeaky floorboard even squeaked) and stopping just outside the bathroom door. They sounded like the slow footsteps of an old man, not the energetic steps of us young people. I did the only thing I could think of: I called out "I'm in here right now, Grandpa, but I'll be done in a sec." After I spoke I heard nothing else- no retreating footsteps, nothing. When I left the bathroom I immediately walked through the entire house including the basement, checking every room. I then went outside and checked the old barn, the chicken coop, the garage, the woodshed, the smokehouse and the old outhouse. No one else was there on the farm.
Sharon told me later that once she was in the basement taking clothes out of the dryer and folding them when she heard the same kind of footsteps descending the basement stairs. These stairs were completely open except for handrails so she could see that no one was there, yet the sound of footsteps continued clear to the bottom of the stairs! Sharon beat a hasty retreat through the outside basement door, called her dog, got in her car and just drove around until she figured that someone else would be home. I think old Grandpa liked to pick on her for some reason. :)
I never felt threatened or uneasy in that house. It was a nice place to live and I enjoyed my stay there, even if we did have an extra roommate.