F.E.A.R. was an AI (artificial intelligence) created by Professor Rourke, with the assistance of his lab-assistant, Briggs. It was created for the sole purpose of destroying the Spy-Busters, but not via conventional means; rather than attack them physically, it instead sought to break their minds. Using its unique powers to transport the Rangers into several different simulations of reality where the teens were then forced to face their worst fears. It was not successful in this endeavor, and was seemingly destroyed by the Rangers in the real world.