Though it existed only for a short time, its warriors were ferocious and deadly, and capable of infesting any creatures they encountered. Consisting of Hydralisks, Mutalisks, Ultralisks, Zerglings, Drones, Overlords, Queens, and later a unique strain referred to as "Roverlisks" (by General Duke), the Brood was assembled after the death of the Overmind by Kerrigan as one of the assault Broods of her new Swarm.
The Kukulkan Brood was formed on Char by Kerrigan after the death of the Overmind. The Brood remained there protecting the new Hive Cluster until a signal from am artifact on Bhekar Ro briefly threw the Zerg into chaos. She then ordered the Kukulkan Brood to locate the artifact and capture it.
The Brood used Behemoths, a massive strain of Zerg transport meant for carrying large numbers of Zerg through space, to travel to Bhekar Ro. The Swarm landed there and began infesting the world, building Hatcheries, Creep Colonies, and other structures so as to increase their numbers. In doing so, they infested "Old Blue", a sky-blue colored dog belonging to one of the colonists, and incorporated his genetics into a new strain of Zerg called the "Roverlisk". Endowed with traits including a heightened sense of smell, this was the Brood's only distinctive breed.
After the Protoss arrived, the Kukuklkan Brood began multiplying, producing more and more creatures including Guardians and Scourge, and fighting the Protoss. A huge melee ensued when the Terran Dominion under Edmund Duke also arrived, though the Zerg and Protoss were numerous and powerful enough to defeat the overconfident Terrans without ever letting up their assault on one another.
Eventually, the Xel'Naga artifact culminated into a new life form, and in its spectacular birth, the creature absorbed every creature and building of the Kukulkan Brood, as well as every Protoss soldier, destroying the Brood completely.
The Kukulkan Brood is named after Kukulkan, a feathered serpent god in Mayan mythology, better known Quetzalcoatl.