Rachel Weisz and Daniel Craig at the Wake Up Dead Man: A Knives Out Mystery premiere ✨ 📸: Getty Images | Digital Spy

Robert Hanssen, an FBI agent, was ironically given the critical task of finding a mole within the Bureau. Little did his superiors know, Hanssen himself was the mole they were desperately seeking. Beginning his clandestine activities in 1979, Hanssen sold highly classified information to the KGB and later to its successor, the SVR, in exchange for substantial sums of money and valuable assets. Throughout his espionage career, Hanssen compromised numerous operations and revealed the identities of