Year 115 (CXV) was a common year starting on Monday of the Julian calendar. In the Roman Empire, it was known as the Year of the Consulship of Messalla and Vergilianus (or, less frequently, year 868 Ab urbe condita). The denomination 115 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 is cut off in southern Mesopotamia after his invasion of that region.
• Trajan captures the Parthian capital of Ctesiphon.
• The Diaspora Revolt erupts almost simultaneously across various Jewish Diaspora communities in the empire's east, including Egypt, Libya and Cyprus.
• Alexandria in Egypt is damaged during the Jewish-Greek civil wars. Marcus Rutilius Lupus, the Roman governor, sends Legio XXII Deiotariana to protect the inhabitants of Memphis.
• A revolt breaks out in Britain; the garrison at Eboracum (York) is massacred.^[1]
• The Pantheon of Agrippa is reconstructed in Rome.

• An earthquake destroys Apamea and Antioch in Syria. The local bishop is held responsible (he will be martyred and remembered as St. Ignatius).

• Pope Sixtus I succeeds Alexander I as the seventh pope of Rome (according to Catholic biographies).

• Pausanias, Greek historian and geographer (d. 180)
• Shun of Han, Chinese emperor of the Han Dynasty (d. 144)

• Alexander I, bishop of Rome (approximate date)
• Dio Chrysostom, Greek philosopher and historian (b. AD 40)