Seen peripherally, at night, or on waking. A substantial share of reports match the known phenomenology of sleep paralysis, which produces a felt presence and an intruder figure with striking cross-cultural consistency. That does not dissolve the category; it explains why the category is so stable, and makes it the best control case in the guide.
Frightening, common, and closely tied to sleep paralysis. If it is happening to you repeatedly, the useful interventions are sleep-side: regular hours, and a doctor if it persists.
Reported with some consistency but carrying no origin claim in the encounters themselves. Filing these as alien is an assumption the listener adds.
Degree of embodiment: 3, comes and goes
Scale, 1 to 5
5 is an ordinary biological body. 4 is physical but manifests oddly. 3 comes and goes. 2 is energetic or subtle. 1 is consciousness with no persistent form. Note that this tends to fall as a tradition ages.
E: recurring reports
Source code
Described by many apparently unconnected witnesses. The strongest category in the guide, and the smallest.
Sleep paralysis
Mechanism
On waking or falling asleep, the body's muscular atonia can persist into awareness, producing immobility, chest pressure and a strongly felt presence. It generates an intruder figure with remarkable cross-cultural consistency, which is why the old hag, the mara and the modern shadow person describe the same thing.
Sleep-state phenomenon
Practice-side
Strongly associated with sleep paralysis and the hypnagogic state. Genuinely frightening, and the fear is not evidence of anything beyond the mechanism. Sleep deprivation and disrupted schedules make it more likely, which is worth knowing before deliberately disrupting your sleep to induce it.
Deliberate contact work
Read this first
The hazard in this subject attaches to the method, not to which name you aim it at. Ouija work, invocation, sustained channelling, induced hypnagogia, deliberate sleep deprivation and hypnotic regression are the practices associated with difficulty, and a session aimed at a benevolent civilisation is not safer than one aimed at something considered lower. What raises risk is doing it alone, doing it repeatedly, doing it while sleep-deprived, and doing it with an existing vulnerability to psychosis, mania or dissociation. People who get into trouble here overwhelmingly got there through practice, not through reading.
Who should be careful
Practice-side
Anyone with a personal or family history of psychosis, bipolar disorder or dissociative conditions, anyone in acute crisis, and anyone isolated from people who would notice a change in them. Intensive contact practice is destabilising by design (that is what it is for), and destabilisation lands hardest on people already close to an edge.