Derro was a male Ferengi who, as of 2379, served as the Ferengi Ambassador to the United Federation of Planets. At a diplomatic cocktail function in Luna's Lunasphere Artemis, Ambassador Derro tried to sell Federation President Min Zife on his idea to "modernize" the Federation economy. (TNG novel: A Time to Heal) Derro had a long-time acquaintance with Ezri Dax, to whom he owed a great debt. His information on Sekki was considered only a small payment against that debt. (ST novel: A Singular Destiny) It is unclear to whether Derro's debt was to Ezri herself, or one of Dax's previous hosts.