Year 15 (XV) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Caesar and Flaccus (or, less frequently, year 768 Ab urbe condita). The denomination 15 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.
- Early (approx.) – Emona (on the site of modern-day Ljubljana) is founded by Legio XV Apollinaris.
- May – As part of his campaign against the Germanic peoples, Germanicus captures Thusnelda, wife of Arminius.
- Summer – Germanicus launches a two-pronged attack from Vetera and Moguntiacum. On his return journey, he recaptures the aquila of Legio XIX and visits the battlefield of the Teutoburg Forest. Germanicus arranges the burial for the remains of Varus' army.
- Varna (Odessus), on the Bulgarian Black Sea Coast, is annexed to the Roman province of Moesia.
- In Rome, the selection of civil servants passes from the people to the Emperor and the Senate.
- The river Tiber floods parts of Rome.
- Valerius Gratus is appointed Prefect of the Roman province of Judea.
Arts and sciences
- September 24 – Vitellius, Roman Emperor (d. 69 AD)
- November 6 – Agrippina the Younger, Roman empress (or possibly 16) (d. 59)
- Apollonius of Tyana, Greek philosopher (d. c. 100) (approximate date)