"A fool trusts his eyes. A wise man fears every rock is a deepstalker"

--Dwarven saying.

Possibly the strangest of all the creatures found in the Deep Roads is the deepstalker. Tezpadam, as the dwarves call them, hunt in packs, generally by burrowing underground and then striking when their prey is in their midst.

Stalkers come in several types. Spitters have venom glands and can spit secretions that slow or injure their prey. Jumpers hurl themselves at their targets, knocking them down and making the kill easier. The most common variety scares its prey, leaving the unfortunate victim helpless against the rest of the pack.
—From Codex entry: Deepstalker

One of the few natural, non-darkspawn creatures to live in the Deep Roads, the deepstalker is a reptilian cave-dweller known for burrowing into the stone paths of the Deep Roads and ambushing prey, usually nugs. They hunt in packs, attacking with round mouths full of serrated teeth or spitting poison from venom glands. Although a single deepstalker poses little threat to any experienced explorer, packs can be quite lethal.
—From Codex entry: Deepstalker