Year 491 (CDXCI) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Olybrius without colleague (or, less frequently, year 1244 Ab urbe condita). The denomination 491 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.

This article needs additional citations for verification. (April 2019)

• Approximate date - John Malalas, Byzantine chronicler (d. c. 578)^[2]

• April 9 – Zeno, Byzantine Emperor
• Peter the Iberian, Georgian theologian and saint