Their only appearance is during the Challenge "Find and kill the Leper in 30 seconds". They spawn once the counter starts, in a spawn point far away from where the drill is placed, and proceed to head out of the map as soon as possible. Feral Instincts are most helpful to find it due to the instinct's ability to outline every Cryptid on sight. The Weapon Specialist Upgrade will also do this, as well as giving a bottomless magazine and a damage boost, all of which assist in killing the Leper more quickly.
The Lepers' behaviour is much different compared to all other cryptids, as the Leper will run away from all players and towards an unreachable area. The best way to identify them is by using Feral Instincts and looking at further parts of the map. They resemble a Hunter, therefore they're easier to identify at an earlier stage on Regular or Casual difficulty, where Hunters aren't common. Another distinguishable feature is the lack of red in the facial region, unlike much of the other cryptids.
- They're not affected by the Tank class upgrade.
- Lepers can attack the player, if it is attacked and is right next to the player. They do the same damage as Scouts.
- In extremely rare occasions, Lepers will attack the drill.
- A shot with the Hypno Knife will kill one instantly.
- Should the Leper die by a Vulture Drone or a Sentry Gun, it will result in an automatic failure of the challenge. The Leper can also (rarely) abandon the map through another spawn point nearby its location before the timer runs out, ruining the challenge very early.