Head Crabs (because there isnt enough half life references already)

[Man of San]

A random antag critter, that constantly tries to latch onto people. It only has a single ability, that being 'Lunge', which it uses to attempt to latch onto peoples heads and bring them into crit. In order to avoid being latched onto and critted, the person getting crabbed must resist. Upon latch, the crab will deal about 10 brute damage every 7 seconds. While not on somebodies head, they are relatively easy to kill with a few strikes from a fire extinguisher or (strangely enough) an instant kill from a crowbar. Upon a successful latch, they will take control of their bodies. These zombies have lesser health (about 20% less than a normal human), move slower, and can't really use most equipment, but do have decently high damage claws that can break through windows.