There is a wandering angry critter on ambient mode in PA 8.2.
He is quite fast once he sees the player (and then won't leave them alone), and his model is ghostly has a knife. After stabbing he teleports away to repeat the process.
He seems to appear when the Krampus event occurs, but as I've never encountered Krampus (an event which happens every night, even on Ambient) due to the magic of the new debug commands, it's possible this creature only spawns at night.
(thank you DrNose for those new debug commands, being able to del.Krampus and scrape the event off the map in this mode is a life saver)
This creature sometimes disappears after a reload, but always comes back. He is persistent and annoying, sometimes camping the bedroom and preventing sleeping by stabbing the player every time they try to sleep.