StarCraft II: Wings of Liberty/Zerg units

Some Zerg units have the ability to morph into an altered or different form by spending time in some sort of cocoon. Although perhaps beneficial, morphing a unit costs resources.

Hydralisk


It has not been confirmed whether or not Hydralisks will be featured in StarCraft II. They have appeared in several concept images, and even in the cinematics, but this does not necessarily mean that they are actually set to appear.

Their appearance have changed slightly in StarCraft II. The most notable difference is their scythes, which now boast more spikes than in StarCraft. Their face is also slightly different from what it was before.

Mutalisk


Strikes Multiple Targets again.

Queen
Only one per player can be produced.

Ultralisk
Featured in some game builds; now has 4 scythes instead of 2.

Zergling
New ability to mutate into suicidal "Banelings" that can roll across the terrain.

Baneling
This green rolling unit is mutated from the Zergling. It has a suicidal attack that deals about 40 damage.

Corruptor
Attacks air units and "corrupts" them rather than destroying them.

Nydus Worm
Can be used to transport small units such as Zerglings underground.

Roach
Has a fast regeneration rate.