Bogsbane

The Bogsbane are a bit of an enigma in terms of how they come to be created. While Pale Druids know that they were originally humanoid that died in the Aetzirian Bogs, they don't know exactly how they come back to life as a Bogsbane. The current theory is that the dead body is filled with the slightly magical and poisonous bog waters, animating the dead body back to life once it has enough magic energy to do so. Since it needs a good amount of it, the body itself becomes bloated and bigger than before. Because the spirit has already moved on, the body is left empty and without any kind of moral or logical guide for its actions.
Travelers need not to worry about any moral ambiguities about these creatures, they are as dangerous and feral as any kind of other monster one would encounter. They don't seem to hold on to any kind of memories when they come back, and many people have simply made peace with the fact that these creatures are not the people they once knew in the past.