A.D. 81 (LXXXI) was a common year starting on Monday of the Julian calendar. At the time, it was known as the Year of the Consulship of Silva and Pollio (or, less frequently, year 834 Ab urbe condita). The denomination A.D. 81 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.

• September 14 – Domitian succeeds his brother Titus as emperor. Domitian is not a soldier like his two predecessors, and his administration is directed towards the reinforcement of a monarchy. By taking the title of Dominus ("lord"), he scandalizes the senatorial aristocracy. Romanisation progresses in the provinces, and life in the cities is greatly improved. Many provincials – Spanish, Gallic, and African – become Senators.
• The Arch of Titus is constructed.
• Pliny the Younger is flamen Divi Augusti (priest in the cult of the Emperor).

• The silver content of the Roman denarius rises to 92% under emperor Domitian, up from 81% in the reign of Vitellius.

• Possible date of the First Epistle of Peter.

• Deng Sui, Chinese empress of the Han Dynasty (d. 121)

• September 13 – Titus, Roman emperor (b. AD 39)^[1]
• Artabanus III, king of the Parthian Empire