Zergling

The Zergling is the first non-worker unit the Zerg are able to build in the game. The Zergling is quick, agile, small, and is most effective when produced en masse. The Zergling only requires one Zerg building beyond the Hatchery to create, has a very low mineral cost, and is produced in packs of two, so it is the ideal unit for early game Zerg.

Individually, Zerglings are weak units with only 35 hit-points and deal a measly 5 damage per attack. However, their rapid attack and movement rates, and speedy construction turn them into powerful weapons. Upgrades are available to increase the Zergling's killing power; unit movement can be quickened, rate of attack may be increased, the player can augment attack power and defense, and the Burrow ability allows the Zergling to hide unseen by the enemy.

A widely popular tactic is the Zergling rush. Players exploit the low cost of creating Zerglings and the speed at which the units can be created to build up a large attack force extremely early in the game to cripple or destroy the enemy before he or she is ready to counterattack or defend.

Appearance
The design of the Zergling varies from cinematics to in-game, and it changes again for its cameo in Warcraft III--this design is also used in StarCraft: Ghost. They also came in World of Warcraft, with another new design. This can often be attributed to and explained by the "natural" state of the Zerg. The creatures are ever evolving and changing due to assimilation of new species and traits that upgrade the zerglings effectiveness, and thus appearance.

In StarCraft, they are bipedal creatures with Velociraptor-like legs. They have three webbed toes on the end of each. Protruding from below their head are two arms ending in scythe-like claws. When zerglings stand still these scythes fold down against their stomachs. Zerglings run by hopping on all four lower limbs, and attack by extending their upper claws and slashing down, then quickly stabbing forward and slashing with the lower before the first motion ends. They can be upgraded to do this even faster, via adrenal glands. This design is based on the picture in the manual; in-game, they're slightly different (primarily in the upper claws).

In StarCraft's cinematics they look rather similar. However, they're much thinner, their head is more separate from the body, and they lack the upper arms. Their scythe-arms are more agile and do not tuck below the stomach, and they stand more upright. They hop the same way, and attack with quick alternating slashes from each claws. Their heads are more rounded in this form, and their chests are quite thin and have very visible ribcages; they somewhat resemble a hydralisk in this incarnation. Also, their rear legs have less joints, and simply go straight back then bend straight down when they stand still. They're more agile than the other forms, and have been seen rearing up and leaning to the side in order to dodge incoming fire. Despite having less pairs of weapons, these seem to be the most dangerous incarnation of the Zergling.

In Warcraft III, they look like dogs with chitinous silver armor on their backs. Scythes protrude diagonally about halfway between each set of limbs. Massive mandibles are found on their seemingly eyeless heads. They attack by slashing inward with their scissor-like claws.

In StarCraft: Ghost they look similar, but have sleeker armor, a more catlike form, and longer scythes. They attack with a 1-2 punch motion with their claws, and can also do a jumping double-slash.

In World of Warcraft, they look much like in Warcraft III but are shorter, fatter, lack the spiked tail, are solid brown, and have wider mouths. They just look generally cartoony, befitting their status as non-combat vanity pets.

History
Zerglings are a modified form of the Zz'gashi Dune Runner, a form assimilated into the Zerg Swarm. They are approximately 1 meter long, although they have been reported to have grown up to three long and one high. Zerglings are the most numerous zerg mutation, as their DNA structure allows two zergling to spawn from a single larva. They require a 'spawning pool' to be formed, and this coupled with their webbed feet hint that they may be partially aquatic. They are, after all, quite froglike--at least in their original design.

Zz'gash is a planet on the edge of Protoss space, and it seems that Zerglings were only recently added to the Zerg Swarm.

The Zergling in StarCraft: Ghost
Zerglings in StarCraft: Ghost maintain their burrowing and health regeneration abilities. In addition, Zerglings gain a "bloodlust" ability, which increases their damage and possibly speed while Zerglings move in groups.

The Zergling in StarCraft II
Zerglings have continued to evolve during the time leading up to StarCraft II. They can can quickly transform into a glowing green creature called a "Baneling" which rolls around the battlefield and kills opponents with a suicide attack. The Baneling appears to do 40 damage at this time.

The Zergling seem to have a slightly changed build, with two large scythe-like arms from their backs and very small insectoid wings. The Zergling cannot fly but it may perform short glides while moving.

Upgrades

 * Burrow
 * Melee Attacks
 * Carapace

Metabolic Boost
Increases Zergling speed.
 * Cost: 100/100
 * Upgraded at: Spawning Pool
 * Requires: none

Adrenal Glands
Decreases cooldown time to 6.
 * Cost: 200/200
 * Upgraded at: Spawning Pool
 * Requires: Hive

Devouring One
The Devouring One is a Zergling hero, slightly stronger and faster.