High Quality Content by WIKIPEDIA articles! A mole (also called a defector in place, an informant, and in the Mafia a rat) is a spy who works for an enemy nation, but whose loyalty ostensibly lies with his own nation`s government. In some usage, a mole differs from a defector in that a mole is a spy before gaining access to classified information, while a defector becomes a spy only after gaining access. However, others use the term mole to describe any agent of a foreign power within a government organization.