The Zerg are a race of innumerable, advanced insectoid aliens with the purpose of gaining genetic perfection. The infinite numbers of these unique aliens gave them the distinct name of the 'Swarm' due to the overwhelming amount of organisms they deploy in-battle to destroy their foes. The original Zerg were discovered on Zerus by the Xel'naga, Amon, who gifted them the Purity of Essence. This divided the race into two types, however: the altered Zerg Swarm and the original Primal Zerg who avoided Amon's doings. Since their creation, the Zerg has swarmed the galaxy over and over again under different leaderships, among them being the infamous Sarah Kerrigan, the Queen of Blades. Many has happened since the former human gained and regained control of the Swarm, but there is one thing that will never change of these exotic beings. They are the Swarm, and nothing will stop their advance.
Battle vs. Arachnids and Tyranids (by Deathblade 100 and Monkey Doctor 33)