|Centuries:||1st century – 2nd century – 3rd century|
|Decades:||70s 80s 90s – 100s – 110s 120s 130s|
|Years:||100 101 102 – 103 – 104 105 106|
|103 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||856|
|Chinese calendar||壬寅年 (Water Tiger)
2799 or 2739
— to —
癸卯年 (Water Rabbit)
2800 or 2740
|Coptic calendar||−181 – −180|
|- Vikram Samvat||159–160|
|- Shaka Samvat||25–26|
|- Kali Yuga||3204–3205|
|Iranian calendar||519 BP – 518 BP|
|Islamic calendar||535 BH – 534 BH|
|Minguo calendar||1809 before ROC
|Seleucid era||414/415 AG|
|Thai solar calendar||645–646|
Year 103 (CIII) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Traianus and Maximus (or, less frequently, year 856 Ab urbe condita). The denomination 103 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.
- Emperor Trajan and Manius Laberius Maximus become Roman Consul.
- Pliny the Younger becomes a member of the college of Augurs (103–104).
- Legio X Gemina moves to Vienna, where it remains until the 5th century.
- In Palmyra, Syria, a Temple of the Sun is erected to the god Baal.