Gantua

The Gantua, otherwise known as the God-Beasts, are colossal, divinely-created animals which roam the Primeval Wilderness of Breis. The herbivorous Gantua feed on the vast trees of the interior, while all but the largest predatory Gantua feed on the thunderbeasts, the unique saurian and avian fauna of Breis.
  Unlike other continents, Breis is not occupied by nations formed by divine pact or mortal determination. Instead, each nation of Bries occupies the broad plateau of a grazing Gantu's back as it roams.
  For logistical reasons, war is almost unheard of in Breis, but Breisian city states do live under the threat of predatory Gantua attacks. Civic defences are therefore directed towards preserving the city and population against sudden movements and other side-effects of Gantu on Gantu combat, and to fending off such attacks where possible.
  Gantua are divided into five size categories by the peoples of Breis:

• Gantu Excelsior - Protas is said to be the first of the God-Beasts, and houses the undisputed capital of Breis. This truly monumental beast is in a category all its own, and the extremis carnivore the Tarrask is its only natural threat.
• Gantu Extremis - City-sized gantua are rare; there are only twelve known grazing Gantua extremis on Breis, each one the seat of one of the great nations of the continent. At least two more are known to have died, both falling victim to the mighty city-slayer Tarrask, the only carnivorous extremis and the continent's undisputed apex predator.
• Gantu Superior - Carrying major towns, Gantua superior often act as trailblazers for the extremises, locating predators that could threaten a Gantu extremis, but might be too slow to catch a superior. Superiors also act as go-betweens for the extremis cities, not being large enough to trigger the bigger Gantua's territorial instincts. Superior predators are rare, but pose a threat even to a Gantu extremis.
• Gantu Major - Large enough to support a small village or even a town on their backs, Gantua major who have not grown to full size may be occupied with an eye to expansion, while full grown majors may play host to small and specialised suburbs of larger settlements. Predatory Gantua major usually hunt in packs, although even alone they would be a threat to a stationary city.
• Gantu Minor - Gantua minor are too small to support any settlement. Some of these are immature, others are simply smaller than their great brethren. The latter group may be used as battle mounts for outlying fortifications protecting a settlement from predation. Carnivorous Gantua at this scale are usually scavengers.