romeo
In the world of espionage, the romeo is a male who is carefully placed within a high level government agency to seduce lonely females placed high in the government,and use emotional and/or romantic blackmail to gain sensitive information about the government's activities.

Females also were used in this capacity during the cold war, and were thus called romiettes.
The Warsaw Pact intelligence agencies routinely placed romeos into western governments to engage in subversive activities and influence.