Federal Bureau of Investigation

The Federal Bureau of Investigation, or FBI for short, is the domestic intelligence and security service of the United States of America, and its principal federal law enforcement agency.

History
The FBI were called when Doctor Octopus kidnapped Felicia Hardy. The investigation was headed by Agent Ford.

Nick Fury told J. Jonah Jameson that the FBI along with the CIA were in the dark about the existence of S.H.I.E.L.D..

Background
It's possible, though never specified, that the men who arrest Tony Stark in were FBI agents.