Gonarch

Appearing in the first-person shooter computer game Half-Life, Gonarch, or 'Big Momma' as nicknamed by the developers of the game, is the mother of all headcrabs. It is a boss featured in one of the last chapters of the game, called "Gonarch's Lair".

Gonarch appears to have no partner, so it may be hermaphroditic. Its anatomy is similar to that of the headcrab, with an apparent armour-like exoskeleton, four spindly legs, but it is also hued a mottled blue, with a sac protruding from its belly, from which underdeveloped baby headcrabs constantly spawn. The Gonarch has no visible head, eyes or mouth. The mother headcrab is viciously territorial, and is remarkably speedy. One can tell when the Gonarch is approaching when they hear a horse-like galloping sound, or when it unleashes an elephant-like cry. The animal will attempt to crush intruders with its sharp legs. It is extremely difficult to kill, taking almost everything in Gordon Freeman's arsenal (and surviving more explosive damage than even a Gargantua).

The player, as Freeman, visits "Gonarch's Lair" near the end of Half-Life, in the 15th chapter of 17. To finish the level, the player must battle Gonarch while it runs around and gives birth to baby headcrabs. During the battle Gordon can bathe in a puddle of semi-clear liquid, which has a healing effect, on a floating platform behind a rock where Gonarch or its baby headcrabs cannot reach him. After defeating Gonarch, the player jumps into a portal taking Freeman to the next chapter.

The player faces the game's final boss, Nihilanth, in the last chapter of the game.