We're corrupt in a good way.
~ Dave Norton

The Federal Investigation Bureau is a law enforcement agency and an enemy faction in the Grand Theft Auto Series. They serve as major antagonists in both Grand Theft Auto IV: The Complete Edition (including GTA IV, TLAD and TBOGT) and Grand Theft Auto Online. However, they appear with a larger role as one of the two secondary groups of antagonists and the collective eleventh antagonists in Grand Theft Auto V. The FIB are truly related to the FBI (Federal Bureau Investigation). It has numerous corrupt members.

Grand Theft Auto V

The FIB plays a major role in the game's storyline. Its known members are Steve Haines, Andreas Sanchez and Dave Norton who gives missions to Michael De Santa, Franklin Clinton, and Trevor Phillips who gives out attacks on IAA (International Affairs Agency) whom the FIB has huge rivalry with.