I was playing Minecraft 1.8 Vanilla alone on a private realm which I have no privileges on in survival mode with no mods or hacks and I was in the mines when I was hit by a potion, I looked around but there was nothing there. I ran further down the hall to a dead end turned around and started to drink milk when I was hit again, still nothing there! Again I was hit multiple times causing my death and major loss of resources. I lost my entire maxed out inventory, body and 55 levels. I went back seconds later and there was no trace whatsoever of my death. My body didn't even drop on the ground when I died, or at least I couldn't see it. Perhaps it was invisible, perhaps it glitched through the walls. There was no fire or lava (20 blocks away) close enough to have accounted for the complete disappearance of my entire inventory and 55 levels.