Tunneler

"They'll start emerging throughout the Mojave in time, might be years. Probably less. They breed fast, hunt in groups, more than enough to bring down the strongest in the Mojave. Once they draw blood... Seen them tear apart Deathclaws... Deathclaw might get some, but the rest will swarm it, tear it apart, like Denver hounds."

- Ulysses

Tunnelers are creatures found in the Divide in 2281.

Background
Tunnelers were the pre-War inhabitants of Hopeville who have taken refuge underground during the Great War. After, they were heavily mutated by radiation of the Divide with a particular mutation adapted for underground life. They are predators, making their nests and living beneath the ground in the Divide. They lived underground all the time and had no knowledge of the surface world, until atomic warheads detonated when the Courier unintentionally brought a package from Navarro containing a copy of ED-E, that activated several of the nuclear warheads that were still underground in their silos since the Great War, causing great earthquakes and storms, and split open the ground, revealing the world to them. Despite that, they don't like natural light and try to keep beyond the reach of the sun by staying in tunnels and low brightness areas.

By 2281, the tunnelers may pose a threat to the wasteland and the Mojave wasteland in the near future, they can spread across the wasteland by underground tunnels, and form nests in years. Tunnelers reproduce quickly and hunt in large packs, enough to become a threat far greater than any other creature. When they are in packs, they can easily tear apart a deathclaw.

Biology
The tunneler appear to be humanoid lizard-like creatures with dark, scaly skin, large bio-luminescent eyes and chitinous spikes protruding from their shoulders and heads. Tunnelers are found underground, as their name implies, and are noted to be afraid of bright lights and loud noises. Every now and then they will flee from combat and head back underground. This can be seen easily by throwing a flash bang or firing a flare gun at a tunneler. Their over-large eyes appear to be an adaptation to the conditions of their preferred habitat and may be sensitive to light, which would explain their extreme aversion to weapons like flash bangs and flare guns.

Hulking tunneler
If a hulking tunneler hits you, there is a good chance you will be knocked down.

Venomous tunneler
As their name suggests, they are venomous.

Appearances
Tunnelers appear in the Fallout: New Vegas add-on Lonesome Road.