Larval Stalker

The Larval Stalker is a strange monster that is partially invisible - they are difficult to spot but they have a ghostly grey silhouette with a thick, darker outline. They appear to be similar to the Mumbler or the Grey Child in terms of body shape, but they also have a small tail which sets them apart from the above. Additionally, they have very large heads in comparison with their height which suggests that they are quite early in their development, plus the name 'Larval Stalker' suggests that too - there is a mature version named a Stalker which while still small and child-like have a much more mature looking silhouette.

At this stage in their development, they cannot attack - they simply observe curious things such as if Harry Mason were to approach. Like all monsters, they will cause the Radio to make noise causing Harry to be on guard but it is useless to attack as they have no physical form to connect to. Interestingly, their bodies constitution does seem to be affected by Harry's Flashlight - blinding them with the light will eventually cause them to fade away. However, they are soon able to reappear so it's most likely that this simply incapacitates them for a time.

It's clear they are aware of their ghostly form as they will often walk directly towards Harry and then pace around him, giving the impression that they are becoming attached to him - therefore haunting him - which would cause a great deal of stress.

In terms of their symbolism, they are essentially Alessa Gillespie's view on loneliness. She was excluded at home and in her school and she felt invisible. Not being able to make any contact is another factor which goes back to Alessa.

Interestingly, in the game, they are more or less depicted as all black as the PS1 struggled to represent translucent things.