Wildmen are hostile NPC's that the player encounters in The Pitt. They are a separate faction from the Slavers found within The Pitt. They can be found in the Steel Yard when the player needs to venture out and find Steel Ingots. You can also find them as you approach the bridge towards The Pitt.
The Wildmen are either escaped slaves or Slavers that have been exposed to too much Radiation from the surrounding areas. It appears more likely that they are Ex-Slavers since they have their own Weapons and Armor. Ashur refers to them as "crazies".