agent - a representative who acts on behalf of other persons or organizations

agent-in-place - an operative serving as a penetration into an intelligence target

agent provocateur, provocateur - a secret agent who incites suspected persons to commit illegal acts

bridge agent - an operative who acts as a courier or go-between from a case officer to a secret agent in a hostile area

case officer - an operative who also serves as an official staffer of an intelligence service

codetalker, windtalker - a secret agent who was one of the Navajos who devised and used a code based on their native language; the code was unbroken by the Japanese during World War II

foot - a member of a surveillance team who works on foot or rides as a passenger

NOC - an undercover agent who is given no official cover

spy, undercover agent - (military) a secret agent hired by a state to obtain information about its enemies or by a business to obtain industrial secrets from competitors

walk-in - an operative who initiates his own defection (usually to a hostile country) for political asylum