Death Stalker

Death Stalkers are large, dark, scorpion-like creatures of Grimm.

The Emerald Forest, Pt.2
A Death Stalker appears within a cave in the Emerald Forest. Jaune Arc and Pyrrha Nikos walk into the cave, mistaking it for the forest temple. Jaune spots a large glowing object in the darkness and thinking it is a relic, tries to grab it. When he does, the object is revealed to be the glowing stinger belonging to a Death Stalker. This prompts the beast to act by breaking out of the cave and flinging Jaune back into the heart of the forest. Pyrrha prepares to battle, but determines that a retreat is a better course of action.

Players and Pieces
The Death Stalker follows Pyrrha all the way to the abandoned temple, which Blake comments on. It then knocks Pyrrha in front of the others and Yang comments how 'now [they] can die together'. Ruby takes it on by herself, but is forced to retreat, then pinned to the ground by a Nevermore and finally is only just saved by Weiss's intervention. The group retreats to the cliffside. The Deathstalker destroys the bridge, isolating Blake, Pyrrha, and Ren from Jaune and Nora. Eventually Blake is knocked across the gap the beast created while Jaune and Nora join the battle. Ren shoots at its tail, but isn't able to shoot it off before he is flung against a nearby wall. Jaune is the one that comes up with a plan to beat it: recognizing that Ren had weakened the stinger's connection to the rest of the tail; he tells Pyrrha to throw her shield to cut off its stinger, then has Nora smash the stinger into its head with her hammer. This attack successfully kills the Death Stalker; its corpse then falls into the abyss surrounding the cliffside.

Appearance
Much like the other creatures of Grimm, a Death Stalker has a base black exoskeleton as well as white, bonelike plates upon its back with red detailing. One of the more prominent attributes is the glowing golden stinger on its tail. It also has a pair of large claws that it uses to corner its enemies in front of its stinger. The Death Stalker found in the Emerald Forest has what appears to be moss or grass growing on it's claws and torso, possibly signifying that it had been laying dormant in the cave for a long time.

Abilities & Powers
Other than the obvious attacks using pincers, a bite and a sting, not much is known about its attacks as it is yet to perform any. Its stinger appears to glow in the dark, though the exact purpose of this is not known (though it did serve as a lure for Jaune). However, the use of its stinger was only seen once, on Ruby, where it failed when Weiss froze its tail in an ice barrier, saving Ruby. It implies that the Death Stalker uses its stinger like any other scorpion, as a jab for poisoning its prey, but it is unknown what lies in its stinger.

A Death Stalker is also very strong, possessing immense physical strength, as it was able to shatter the rocks around a small cave entrance in order to escape, and several trees of the Emerald Forest while chasing Pyrrha. It was also able to fling Jaune a considerable distance just using its tail. It also has what appear to be battle scars on its body, signifying it has been in some tough battles and managed to survive, indicating a large amount of battle experience. The Death Stalker also seems to have enough speed, able to catch up to a fleeing Pyrrha, even though she had a head start.

It is also highly resistant to damage, withstanding bullets from Crescent Rose, StormFlowers, and Miló with ease, having no effect at all. It has also been shown to resist blades such as Crescent Rose and Gambol Shroud. Despite its resistance to damage, the Death Stalker seems to be slightly affected by strong blows, such as Nora's Magnhild, where it was left disoriented a few times. Somewhat ironically, the only object shown to be capable of piercing the Death Stalker's carapace is the Death Stalker's own stinger, which falls directly into the beast's head after being severed.

Trivia

 * The cave where a Death Stalker emerges from has old drawings of people attacking the monster with sticks and spears. This could signify that the monster had been in the cave since the original war with the Grimm.
 * This is supported by the creature's aged and battle worn appearance, which suggests that it is very old.
 * One of them can be seen in the Opening sequence of RWBY, along with various other Grimm creatures.
 * Death Stalker is also the name of a species of a scorpion.