Descendants of pre-War cattle, brahmin are very weak animals that have been domesticated and herded throughout the years since the Great War. They can be seen wandering in herds around the Mojave Wasteland, albeit rarely.
Through their domestication, they have been used primarily for meat and milk, and their hides are tanned to make leather. Traders use them to carry heavy loads, while others, such as Cook-Cook, keep them as pets.
As a result of the constant exposure to radiation, these formerly normal cows have sprouted a second, independent head. Ironically, after so many years of having this mutation, brahmin which is born with only one head is considered to be mutants. Brahmin also have eight stomachs. According to Rose, male brahmin also has four testicles. Their skin has turned a toasty, dusty orange-red color from the exposure to fallout and their horns have become a dirty brown. Their udders have also grown to be abnormally large, almost to the point of dragging on the ground.
Brahmin has a minuscule amount of Hit Points, and as such pose, only a very minor threat, if any, even for low-level characters. When brahmin attack, they strike with their horns and batter into a foe. This is not highly damaging and is rarely seen, as brahmin generally flee when attacked. When a brahmin is killed, it will let out a loud bellow and flop to the ground.
Mad brahmin are brahmin that have been frenzied, whether it be from radiation poisoning or other traumatic experiences. They will always be hostile to the player character unless they have the Animal Friend perk.
Malnourished brahmin is a sickly brahmin that has been neglected and cannot find food on its own. Their meat is unaffected by their malnutrition. They can be found in various locations throughout the Mojave Wasteland, most notably Matthews Animal Husbandry Farm.
Malnourished brahmin calves are young brahmin that cannot find sufficient food to maintain full health, usually because they have been deserted by their owners. Their meat is unaffected by their malnutrition. They can be found across the Mojave at places such as the Matthews Animal Husbandry Farm. There is also one in front of Raul's shack.
Water brahmin serves a similar purpose to caravans in Fallout: New Vegas, although the only goods they carry are sacks of water, essential for life in the Mojave Wasteland. These brahmin assist the Crimson Caravan in delivering water where it is needed. Fixed locations are near Miguel's Pawn Shop and the 188 trading post. Although they carry water packs, they won't yield any water when killed and looted.
These are brahmin that is owned by the Fiends and are located at Cook-Cook's fort. They are not part of the Fiend's faction cell and are friendly to the player character unless provoked. There are two unnamed fiend brahmin and one named "Queenie," whose death will frenzy Cook-Cook.
If the Courier crouches, disarms their weapon, and presses the "activate" button while in front of a brahmin, the brahmin will tip over (more specifically, enter a ragdoll state). This is known as brahmin tipping. Every time a brahmin is pushed (even if they are already on the ground), it counts toward the Knocked Upchallenge. Do note that doing so multiple times may kill the brahmin.
Brahmin that is used by merchants to carry their wares are usually referred to as "pack brahmin." If they are carrying water, they are known as "water brahmin."
It is impossible to sever or destroy one brahmin head without also destroying the other.
There is a giant brahmin skeleton (about 2 times larger than normal skeletons) found south of Jacobstown.