Mumbler

Mumblers are small monsters which have large gaping mouths that when closed appears like a deep cut across their face. Their mouths are typically pooling with drool or blood through the centre, with droplets often reaching the ground. They share a lot of similarities with the Grey Child in their form and their behaviour, but unlike Grey Children instead of using knives they have natural tri-pointed claws with extremely sharp blades. They are named the Mumbler because although they are usually silent, they will make a haunting mumbling sound as they close in on their prey.

They either attack on their own or in groups of up to three - it's also possible that they will lunge at their prey and cling on whilst attacking which is another behaviour that is similar to a Grey Child.

The reason they seem so similar to Grey Children is that they were used in place of them in some territories, as some censors (Europe and Japan to name but a few) thought they looked a little too much like a human child. As the Grey Child is the first monster encountered by Harry in Silent Hill, it's possible that the Mumbler will be the first monster he encounters. However the Mumbler does appear later on in the game in it's originally intended place.

Finally, they share some similarities to the Shambler from the original Quake. It's possible that Alessa Gillespie was read H.P. Lovecraft's Cthulhu Mythos where a creature named a Dimensional Shambler existed. As Alessa's twisted perceptions are what creates the symbolic monsters of Silent Hill. Although it's equally possible that the Mumbler is based off any number of monsters from different stories.