Pathfinder: Shadow of Chernobyl
Chimeras are, or were, humans, elves and orcs that had spent too much time in the Zone.
Whilst their minds remain largely intact their extreme exposure to magic has inflicted great change on their bodies. For many this means taking on aspects of animals, fur sprouting from their bodies, additional limbs growing from shoulders or even skin turned to iron. The effects of magic are wild and unpredictable.
Not everyone can survive the process and it is likely that any Chimeras you meet are the hardiest of individuals.
Chimeras don't all share a particular goal or outlook and so they can be found scattered amongst any groups of similarly minded individuals. Their temperaments are likely to be as individual as their bodies are.