While not generally thought of as a Wesen species, Grimm share a bloodline trait separating them from normal humans: they are capable of seeing the true form of a Wesen, typically when the Wesen is startled, afraid or otherwise emotional. It is implied that a member of the next generation receives the gift as the last approaches their deathbed or is murdered, the only guarantee is that it seems to manifest earlier in women than men. It is a long-standing tradition that Grimms hunt Wesen who attack the general population- traditionally killing them by decapitation- and keep journals recording their encounters with Wesen for future Grimms to learn from. Over the years, the Grimm have acquired a reputation as semi-mythical boogeymen. This reputation extends to the highest levels of Wesen society, with even the royal families doubting the existence of a good-natured Grimm. Other than their ability to see Wesen as they truly are, Grimm also seem to possess a natural ability for profiling people, and are highly skilled at physical combat. They are also resilient to such magic as the Coins of Zakynthos, which makes ordinary humans and Wesen become overconfident, power-hungry, and obsessive. They have been guardians of the Coins for many generations. It has been suggested that if a Wesen ingests the blood of a Grimm, it will strip them of their powers and abilities, essentially turning the Wesen into an ordinary human, though this has only been confirmed with a Hexenbiest. It should be noted that most Wesen give an involuntary shudder when they notice that a Grimm is observing them. This may simply be because they feel exposed at being seen, but wesen may in fact have the ability to sense a Grimm seeing them. There is also an unexplained connection to the Verrat that implies that Grimm were key in the Verrats rise to power; whether they are servants or rulers of the Verrat is unknown.
