Deviants are special monster individuals who have survived harsh conditions and have changed to overcome said extremes they've faced. They are known to be similar to normal monster individuals, though different and special in some ways. Deviants are known to have a unique appearance, fighting style, and adaptions in battle. Deviants are also known to sometimes be larger than normal individuals. From these special individuals being far more dangerous and different, only hunters with special permits are allowed to hunt them.

Materials from deviant monsters can be used to craft special Rare X equipment pieces. They are found in the last pages of the crafting menu, and they have some differences compared to regular counterparts.

Wielding the weapons of deviants allows hunters to fill up their hunter arts bars in order to use the hubter arts for battle much faster.

What also makes Deviants different is the added part of their names, such as Dreadking or Hellblade. According to the Guild Master, this is to show respect to how rare and powerful these particular individuals are. The added name also gives a bit of fear into the monster to make them more terrifying.