The Kroot are a species of tall, avian-descended xenos mercenaries, best known as the foremost auxiliaries of the T'au Empire. Lean and rangy, with beaked faces and quills that bristle when they are roused, they hail from the forest world of Pech and range across the galaxy selling their skill in war to the highest bidder.
Their most remarkable trait is a unique evolutionary biology. The Kroot can absorb the genetic traits of creatures they devour, and so their warriors ritually consume the flesh of worthy foes in the hope of inheriting their strengths; it is said that kindreds who once feasted upon Orks grew ever more savage and hulking. Their Shapers, part leader and part spiritual guide, carefully direct what the kindred eat to steer their evolution across the generations.
This makes them both valuable and perilous allies. The T'au prize the Kroot as trackers, skirmishers, and ambushers who thrive in terrain where regimented soldiers falter, yet they also worry that an ill-chosen meal might send a Kroot kindred spiralling into bestial regression. Fierce, adaptable, and profoundly alien in their customs, the Kroot fight for whoever pays them well, though their long alliance with the T'au has bound the two peoples ever more tightly together.