|Centuries:||2nd century – 3rd century – 4th century|
|Decades:||210s 220s 230s – 240s – 250s 260s 270s|
|Years:||239 240 241 – 242 – 243 244 245|
|242 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||995|
|Chinese calendar||辛酉年 (Metal Rooster)
2938 or 2878
— to —
壬戌年 (Water Dog)
2939 or 2879
|Coptic calendar||−42 – −41|
|- Vikram Samvat||298–299|
|- Shaka Samvat||164–165|
|- Kali Yuga||3343–3344|
|Iranian calendar||380 BP – 379 BP|
|Islamic calendar||392 BH – 391 BH|
|Minguo calendar||1670 before ROC
|Seleucid era||553/554 AG|
|Thai solar calendar||784–785|
|Wikimedia Commons has media related to 242.|
Year 242 (CCXLII) 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 Gratus and Lepidus (or, less frequently, year 995 Ab urbe condita). The denomination 242 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 Gordian III begins a campaign against king Shapur I, the Greek philosopher Plotinus joins him and hopes to obtain first-hand knowledge of Persian and Indian philosophies.
- Gordian III evacuates the Cimmerian cities in the Bosphorus (Crimea), as the territory is now controlled by the Goths.
- Shapur I makes a pre-emptive attack on Antioch to drive out the Romans. Gordian's father-in-law, Timesitheus, leads a Roman army to defeat the Persians at Carrhae and Nisibis.
- Patriarch Titus succeeds Patriarch Eugenius I as Patriarch of Constantinople.
- Cao Mao, fourth emperor of the Kingdom of Wei (d. 260)
- Saloninus, Roman Emperor (d. 260)
- Sun Hao, last emperor of the Kingdom of Wu (d. 284)