Roach

Appearance
Roaches resemble upright Cockroaches that can grow to at least a meter tall. They walk on four insectoid legs and are covered in white exoskeleton. Unlike normal cockroaches, the Grimm Roach has multiple red eyes and usually an odd number of antennae. Serrated blade-like constructs are on their arms.

Abilities
The roach is capable of walking on walls or ceilings and hopping long distances to pounce their targets before slashing them open with their arms. While these seem like standard Grimm tactics, the kicker is in how robust the Roach is. Recovered data by the Flagg Institute hints that the Roach possesses a distributed nervous system; headshots are not guaranteed kills and many shots to center mass harmlessly pass through the creature's soft innards. Many reports have been heard of roaches having their heads and sometimes torsos blown off and the creature's legs are still capable of movement, although the movements are violent and unpredictable like a blinded chicken.

Weaknesses
The fastest way to kill a roach is to physically dismember the creature's limbs in some way to lower its mental capacity. As more parts are either cut or shot off, the roach will eventually cease to be able to sustain necessary mental functions and die. Granted the individual flailing parts can still be hazardous.

Author's notes

 * I may or may not have binge-played Dead Space before writing this....