|Centuries:||1st century BC – 1st century – 2nd century|
|Decades:||10s BC 0s BC 0s – 10s – 20s 30s 40s|
|Years:||15 16 17 – 18 – 19 20 21|
|18 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||771|
|Bahá'í calendar||−1826 – −1825|
|English Regnal year||N/A|
|Chinese calendar||丁丑年 (Fire Ox)
2714 or 2654
— to —
戊寅年 (Earth Tiger)
2715 or 2655
|Coptic calendar||−266 – −265|
|- Vikram Samvat||74–75|
|- Shaka Samvat||N/A|
|- Kali Yuga||3119–3120|
|Igbo calendar||−982 – −981|
|Iranian calendar||604 BP – 603 BP|
|Islamic calendar||623 BH – 622 BH|
|Minguo calendar||1894 before ROC
|Thai solar calendar||561|
|Wikimedia Commons has media related to 18.|
Year 18 (XVIII) was a common year starting on Saturday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Augustus and Caesar (or, less frequently, year 771 Ab urbe condita). The denomination 18 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 Tiberius and Germanicus are Roman Consuls.
- A vexillatio (sub-unit or detachment) of Legio III Augusta is destroyed by an ambush in Africa.
- The German chieftain Arminius destroys the kingdom of the Marcomanni.
- Winter – Germanicus Caesar arrived in Syria, as new commander in chief for the Roman East.
- Gnaeus Calpurnius Piso, governor of Syria, ignored the order of Germanicus to send Syrian-based legions, including Legio VI Ferrata and Legio X Fretensis, to Armenia to back him in his planned coronation of Artaxias III.
- Germanicus conclude a peace treaty with Artabanus II of Parthia, in which he is recognized as king and friend of Rome.
- After a flooding of the Yellow River farmers are forced to rebel. Emperor Wang Mang reacts by sending an army (some 100,000 men) against the agrarian rebels. The rebel leaders, concerned that during battle it would become impossible to tell friend from foe, order that their men color their eyebrows red – and this is where the name Chimei ("The Red Eyebrows") comes from.