|Centuries:||1st century – 2nd century – 3rd century|
|Decades:||110s 120s 130s – 140s – 150s 160s 170s|
|Years:||139 140 141 – 142 – 143 144 145|
|142 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||895|
|Chinese calendar||辛巳年 (Metal Snake)
2838 or 2778
— to —
壬午年 (Water Horse)
2839 or 2779
|Coptic calendar||−142 – −141|
|- Vikram Samvat||198–199|
|- Shaka Samvat||64–65|
|- Kali Yuga||3243–3244|
|Iranian calendar||480 BP – 479 BP|
|Islamic calendar||495 BH – 494 BH|
|Minguo calendar||1770 before ROC
|Seleucid era||453/454 AG|
|Thai solar calendar||684–685|
Year 142 (CXLII) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. At the time, it was known in the Roman Empire as the Year of the Consulship of Pactumeius and Quadratus (or, less frequently, year 895 Ab urbe condita). The denomination 142 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 Antoninus Pius orders the construction of the Antonine Wall. The wall stretch 39 miles (63 km) from Old Kilpatrick in West Dunbartonshire on the Firth of Clyde to Carriden near Bo'ness on the Firth of Forth (Scotland). The Romans built nineteen forts and smaller fortlets (milecastles), to protect the border against the Caledonians.
- Municipal doctors are named throughout the Roman Empire.
- First year of the Hanan era of the Chinese Han Dynasty.
- The Chinese Taoist alchemist Wei Boyang, author of the Kinship of the Three, is the first to describe an early form of gunpowder solution.
- Aemilius Papinianus, Roman jurist and praetorian prefect (d. 212)
- Liu Biao, Chinese governor (d. 208)
- Elpinice (daughter of Herodes Atticus) (d. 165)
- Pope Hyginus (approximate date)