A broken one is a fantasy role-playing game monster.
They are a failed race caused by an attempt to merge men and animals. These attempts are usually from crude science or magical spells gone awry. They leave the original man behind, and in his place is a twisted sort of animal man (on a more contemporary note, Jeff Goldblum was sort of a broken one in the movie The Fly).
A broken one will always appear a caricature of a human, with animal features prominent. They may have a tail, or whiskers, claws or even shark-like teeth. Each one of them is unique.
The broken ones tend to band together in small communities far from human settlements and most of them can interbreed. Over many generations a community will become more and more human as the more common human genetic material becomes dominant in the community. They are usually capable or rudimentary manufacturing of basic goods, and they tend to keep small farms (the ones that will eat vegetables at least, some of them will eat only meat).
They are often hunted down by local humans for (mostly imaginary) wrongs. This has given the broken ones a healthy dislike of normal humans in general. Even a community which has interbred themselves to the point of merely being ugly humans, will still stay away from people, due to the memory of centuries of persecution.
As far as combat goes, a broken one can be a formidable opponent for a normal man. They heal from wounds in minutes (some say one of the gods looked down upon them with pity, and granted them this ability). They will usually have some ability related to the animal they were merged with (like extra strength, speed, claws, or even wings in a few rare cases).
From time to time a broken one of exceptional intelligence, powers, and charisma will be born. These individuals tend to lead the communities, and often have animal powers that are far superior to what the actual animal would even have (Cerebus the Aardvark, and the Teenage Mutant Ninja Turtles would be examples of this superior type).