I have a couple stories. Two of them happened to my mom and the other one to me.
When my mom was 13 she was getting ready to go to bed and she had just fallen asleep when something woke her up. She rolled over and looked at her door and she saw some guy standing there. At first she couldn't make out who it was. She thought it was her dad but she realized he was see-through. The guy was looking right at her but she wasn't scared. He was wearing an army uniform and there was this big bloody hole in his chest and blood everywhere. It was her uncle who had died in World War II at the Beach of Normandy on D-Day. After a few minutes he just disappeared.
Later in her life, just after she married my dad, they were at home one day when the phone rang. My dad answered it and it was a guy asking to speak with my mom. She talked to the guy but she had no idea who it was until he said something (I don't know what) that triggered the memory of seeing her uncle so she thought that's who it was. She's never seen or heard from him again. The weirdest thing is he died 10 years before she was born. She thinks he is her guardian angel though she can't figure out why he's hers.
Here's the other story. My story. When I was 7 my Grandpa died and he was my best friend in the whole world. When he died I died too. Last Summer just after I turned 14, I walked into the kitchen to get something and I saw the back door open and someone came inside. I knew it was my Grandpa but he didn't look like himself. The best way to describe it was his whole body was all swollen. He said something but I don't remember what and then he disappeared. Right after, I went and told my brother who still doesn't believe me. The thing is I don't know if it was a dream or not. Right after it happened I knew it wasn't but the next day I couldn't remember.
I know he's watching me all the time making sure I don't do anything too stupid but I don't understand why I saw him that way. Until that day I had never been able to accept his death. I had skipped over the first three grieving processes and gone right to depression but I started to very slowly accept, in my heart, that I'd never see him again.