Wraiths are monsters that are followers of the Thanatos. There appearance changes based on what species they were before they became wraiths.
Wraiths are evil monsters who posses strange and incredible powers. The Thanatos grants them these powers in turn for their loyalty. Though, most wraiths are humans or animals who have joined the Thanatos willingly, some have been forced to become wraiths. This is when the Thanatos drains the person of all good energy. These types of wraiths have no control of their actions whatsoever.
A wraith's appearance depends on what species it was before it became a wraith. Animal and plant wraiths look very much like they did before they became wraiths. Human wraiths, however, take on a much different appearance. They become almost snake-like and their eyes disappear completely. Their hands turn into claws and their legs vanish. All wraiths have either no eyes or clear eyes. They also all have three purple colored rings that glow around their tails, and their tails also emit a black flame-like substance (not counting plant wraiths).
Plant wraiths are very different from human and animal wraiths. There types of wraiths emit high levels of poison into the ground (and sometimes to the air), and though they can not move from their location, they swing their branches or other appendages around violently when a non-wraith approaches. Plant wraiths are most commonly large trees, such as pine trees.
Wraiths grow in strength the longer they stay as wraiths. The chance of something becoming a wraith also depends on it's species. For example, cats, foxes and birds have an extremely high chance of becoming wraiths, while for domestic dogs an horses this is nearly impossible. This is most likely due to the bond certain animals share with humans.