Grimm

The Grimm (グリム, Gurimu), or The Creatures of Grimm, are a sub-species of creatures in Tales of RWBY series created by Monty Oum and Yoshiharu Gotanda. They are the universal antagonists, inhabiting various parts of Remnant.

They are described as "creatures of destruction" that lack a soul; hence, they are unable to use Aura. They are also drawn to feelings of negativity - such as envy, sadness, loneliness and hatred - often congregating towards the source of these emotions.

"For as long as humanity can recall walking the surface of Remnant, so do they remember this wicked force."
 * —Salem, About The Creatures of Grimm.