The real wraith
A Wraith is a type of supernatural creature, that feeds on human's brainfluids and can infect them with high doses of dopamine.
One appeared as monster of the week in the episode "Sam, Interrupted", in which a wraith was feeding on psychiatric asylum patients.
Characteristics
Wraiths feed on brainfluids, which can be extracted through a spike located in its wrists. They introduce it in a weak spot behind the ear to easily get to the victim's brain. Wraiths can use it as a weapon, but it seems to be easy to break. Victims, with their brainfluids sucked, show completely dried brains.
It is shown that the best survival site for a wraith would be a psychiatric asylum, as it is the perfect place to feast on a regular basis--not only the patients' brains, soaked in dopamine, are delicious, but no one in the staff would believe them if they claim that there is a monster killing them, as they were diagnosed as unstable (psychologically speaking) and most of them suffer some form of psychosis, schizophrenia and several other mental disorders involving reality distortions, hallucinations and paranoid or bizarre delusions.
Appearance
As other supernatural creatures, wraiths can look like typical humans. However, their real faces can be seen, and recognized as wraiths, when they are reflected on a mirror. Their true form is that of a humanoid creature with a rotten face.
Known Abilities
It has been shown that wraiths possess an ability to infect people through physical contact, and make them psychologically unstable so they can suffer from severe hallucinations and episodes related to their inner problems. The wraith that appeared in "Sam, Interrupted" revealed that they infect them by elevating a human's dopamine level, and that they actually do not make them crazy--they just let their inner problems and emotions take over with a little help.
The victims slowly become more and more unstable, and depending on the victim, their inner problems will begin to surface as realistic hallucinations (E.g. Dean and Sam Winchester's problems related to their life as hunters and their guilt over the Apocalypse, caused them to have hallucination, as they began to not be able to tell apart reality from fantasy). However, when the wraith is killed, the venom has no longer effect.
Weaknesses
Wraiths are relatively easy creatures to kill, mainly because of their extreme weakness to silver.
Gallery
Ethymology
Wraith is a Scottish dialectical word for "ghost, spirit".