Zerg

The Zerg are a race of creepy insects determined to assimilate all advanced life in the Galaxy. They were originally peaceful, but they were turned evil, then turned back peaceful shortly before joining The League.

The Zerg were originally discovered by the insane Xel'Naga on the planet Zerus. They were gifted with Purity of Essence, whatever that is, making them the counterparts of the Protoss. The Overmind (Who is in no way related to the Gravemind) oversaw the Zerg's peaceful evolution. However, the Overmind was possessed by the Dark Voice and forced to attack the Xel'Naga, driving them away from their Galaxy. They then embarked to the Milky Way, seeking the Protoss, all part of the Dark Voice's grand plan to bring about the apocalypse.

The Zerg then took part in a three-way war between them, the Protoss, and Renegade Humans (Humans not in the League). They captured some strange Ginger Freak and 'infested' her, turning her into a humanoid Zerg. This was all part of the Overmind's cunning plan to free the Zerg from the Dark Voice. Soon after, the Zerg Homeworld of Char was attacked by the Protoss, and the Overmind's Right-Hand Bug was killed. This created a brief mental link between his killer and the Overmind, who then discovered the location of Aiur and launched a full-scale assault. He then relocated to Aiur, which was a good idea considering he had just started an invasion, and got himself killed by the Protoss.

The Zerg were divided between the Ex-Ginger and some freak. The Freak was killed by the Ex-Ginger and she took over the swarm, christining herself the Queen of Spades. After another war, she was de-infested and the swarm divided again.

It was then the Gravemind went to work with his manly charms. He convinced the Zerg leader (No-one knew who it was at the time) to ally with The League and so began a peaceful co-existence. The Overmind's cunning plan worked, with the Zerg breaking free of the Dark Voice's control and returning to their peaceful ways once again. They are now strong allies of the League, and unsurprisingly they are best buddies with the Flood.