Scorpion

This creature poses a threat from a much further distance than she appears, sending her stinger underground to strike you from afar. Her fearsome pincers are just for show, as she lacks a melee attack.

Strategy
Scorpions seldom appear alone, and are most likely to land hits on a player who is currently engaged with a much closer mob. Take care of both with at once with piercing weapons like the Ballista or Railgun.

Their stinger has a fairly long interval between strikes, leaving them vulnerable to close-range melee or shotgun attacks.

Trivia

 * The scorpion's semi-humanoid appearance draws from the Girtablilu of Babylonian myth.
 * The Egyptian Goddess Serket (or Selkis) is also associated with scorpions. She is sometimes depicted as a scorpion with a woman's head.
 * The Scorpion's design has changed considerably since its alpha form, as it once had a much more straightforward arachnid appearance (via David Kay's twitter).
 * The semi-humanoid version in the final release was confirmed to be partially inspired by the Arachnoid from the Serious Sam franchise.