F.E.A.R. Perseus MandateEdit
The Nightcrawlers are a group of highly-trained mercenaries hired to destroy evidence and steal important data pertaining to Project Perseus. Throughout the course of Perseus Mandate, they engage almost all armed opponents they cross paths with, including Delta Force, Replicas, the F.E.A.R. team, and even Armacham's guards. In the later stage of the game, they also have minor engagements with Alma's Apparitions.
There are three different types of Nightcrawlers; the light soldiers, heavy soldiers and the Elites. The force itself is led by an albino Elite, The Nightcrawler Commander. In terms of combat performance, the Nightcrawlers are usually on-par, and sometimes surpass, all Replica and Delta Force units, the Elites have enough skill and endurance to compete with F.E.A.R. operatives.
In Perseus Mandate, the Nightcrawlers are hired by the Senator to steal Armacham Technology Corporation's research. They seem to work under the command of Gavin Morrison, however, they later betray him, and the Sergeant finds a laptop with a recorded message stating the Senator is "becoming more trouble than he's worth." Nevertheless, at the end of Perseus Mandate, the Nightcrawlers manage to capture a sample of Paxton Fettel's DNA and bring it to the Senator, despite their commander and many of their forces are killed, the Nightcrawler force may be bigger than previously thought, as one of the Elites told the Senator the loss of the Nightcrawler operatives is "acceptable".
Like Replica Forces, the normal Nightcrawler soldier share the same voice, hinted they are either clones, or they disguised their voice to hide their identity.