First officer
From Tardis Wiki, the free Doctor Who reference
First officer was an title used by Gallifreyan soldiers.
Once, the Ten killed a squad of Gallifreyan soldiers on Dalgar by hypnotising the first officer to kill the commander, then the second officer to the first officer, and so on. The Ten let Tessno survive the incident so that she could tell Gallifrey about what he had done. (AUDIO: Stop the Clock)