Go-zu oni are outwardly similar to other oni, with powerfully built humanoid bodies of prodigious size, but with the heads of beasts. A typical go-zu oni is 9 to 10 feet tall and weighs between 500 and 1000 pounds. Their skin is typically orange, gray, purple, or brown, and they favor wearing fine robes and well-crafted armor to mark their perceived station as creatures of power, wisdom, and cleverness.

Most oni on the Material Plane pursue their plans for power in the mortal world, but the go-zu oni retain more of their connection to their ancient progenitors in the Outer Planes. They are often encountered near planar gateways, whether intentionally created by diabolists and death cults of all kinds or simply naturally occurring thin spaces in the planar fabric. They travel back and forth between worlds and often consider themselves guardians and guides of the paths of the dead. They may be the first creatures encountered by planar travelers venturing into the realms beyond, and if not precisely benevolent they can be impartial servants who simply assist with the spiritual journey.

Go-zu and Me-zu. While many mortals see beast-headed giants and flee in terror without bothering to learn more about them, there are a variety of different beast-headed giants that mortals all lump together as go-zu oni. In fact, the go-zu oni (also called niutou) specifically refer to those oni with heads like horned bulls or oxen.

Their most common kin, the me-zu oni (also called mamian) have heads like shaggy horses. Others are reported to have heads like predatory beasts, monkeys, or even insects. Whether this indicates a specific caste or rank is unclear but go-zu and me-zu oni often work together as messengers, battle leaders, guardians, and more, and their game statistics are identical.

Soul-Stealers. Many among the go-zu oni cleave more closely to their fiendish ancestors in their hellish realms, and they look for opportunities to enslave and kidnap mortals, spiriting them away into torment and judgment in the Lower Planes.