Year 9 BC was either a common year starting on Wednesday, Thursday or Friday or a leap year starting on Thursday (link will display the full calendar) of the Julian calendar (the sources differ, see leap year error for further information) and a leap year starting on Monday of the Proleptic Julian calendar. At the time, it was known as the Year of the Consulship of Drusus and Crispinus (or, less frequently, year 745 Ab urbe condita). The denomination 9 BC for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.