Pronounced "Bai-et-zoo" or "Bah-ay-tee-zoo"
In a word: DEVILS
There are many various forms of Baatezu Devil Kin.
They are all residents or associates of the Nine Infernal Hells of Baator in some way, and often serve as troops or leaders in the great Blood Wars, the hellish wars that have ravaged the infernal realms for eons.
Infernal armies often employ the use of Hell Hounds in their wars and missions.
Durzagon, a half-fiend
Fiend of Blasphemy
Gathra, an infernal wild beast
Fiend of Corruption
Devils sometimes employ the use of fiendish symbionts