Eric Michael O'Neill (born March 3, 1973) is an American former FBI counter-terrorism and counterintelligence operative. He worked as an Investigative Specialist with the Special Surveillance Group (SSG) and played a major role in the arrest, conviction, and imprisonment of FBI agent Robert Hanssen for spying on behalf of the Soviet Union and Russia. His book written about this experience, Gray Day: My Undercover Mission to Expose America's First Cyber Spy, was published in Spring 2019. He is a public speaker and security expert who currently lectures internationally about espionage and national security, cybersecurity, fraud, corporate diligence and defense, hacking, pursuing dreams and surviving Hollywood.