Oscar Henderson was an officer in the New York Police Department. He was asked by Commander Strebbins to keep an eye on Amy Pond and the Eleventh Doctor as they chased after the Mammoth. He helped Amy find the Doctor by using a police tracker dog named Bismarck. He later met up with Commander Strebbins, who was being controlled by the Vykoid Lars. He claimed to report on the Doctor, but was going to shoot her. Eventually, he gave himself up as a puppet to the Vykoids.
After the Doctor forced the Vykoid leader, General Erik, to disable the Time Freeze, the New Yorkers' minds were sped up to normal speed, causing them to forget the events that had occurred when the Forgotten Army attempted an invasion. Oscar forgot the Doctor and Amy, although he encountered them before they left in the Doctor's TARDIS. (PROSE: The Forgotten Army)