Worms That Walk

Worms That Walk look human-sized caterpillars with six tiny yellow eyes, who masquerade as humans using cloaking abilities. They feed psychically. Like the Ghoul Hounds of Leng, the "Worm That Walks" was previously a Unique Entity that has since been made into a species. Their description has also changed completely, previously being, "looking like a human corpse decayed into tones of green, black, and blue, with dripping pieces of flesh hanging from it."

In the RPG...

The Worms can temporarily cloak themselves by using magic points, but also cloak themselves for longer as someone they have fed upon. They can also gain psychic dominance over someone via an opposed POW roll, which has a 75% chance of succeeding against an average person. They use these abilities to feed upon a victim's life-force (a.k.a. POW). If the Worm does not have psychic dominance over their victim, the victim may break free with an opposed STR roll—24% chance for an average person.
    One interesting trait of a Worm That Walks is that they can only be injured when in their uncloaked form, though they can alter the illusion to look like they have been injured, which opens up many narrative options.

In a video game...

This is my first time reading about Worms That Walk, and I have to say, I really like them. They're horrific and interesting in their abilities. As such, I would definitely include them in a video game. They are quite hard to kill, but as they can essentially fake their own death, this wouldn't really matter.

In a film...

I think a Worm That Walks would make a great horror movie monster.