Year 411 (CDXI) was a common year starting on Sunday of the Julian calendar. At the time, it was known in Rome as the Year of the Consulship of Theodosius without colleague (or, less frequently, year 1164 Ab urbe condita). The denomination 411 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 Honorius sends two Roman generals to deal with the usurper Constantine III in Gaul. They kill Gerontius, Constantine's rebellious general (magister militum) in Spain, then besiege Arles and defeat Constantine III. He is taken prisoner and put to death at Ravenna.
• Following the defeat of Constantine III, the Burgundians and the Gallic nobility proclaim Jovinus, Gallo-Roman senator, emperor of the Western Roman Empire at Mogontiacum (modern Mainz).^[1]

• King Ataulf leads the Goths into Gaul at the instigation of Honorius, who promises to recognise a Visigothic Kingdom if he defeats the several usurpers who threaten the Roman Empire.
• The Alans establish their rule in the Roman province of Lusitania (Portugal south of the Duero River and Spain).
• The Teutonic tribes in Spain join the Roman Empire as foederati (allies with military commitments).

• Ingyo succeeds his brother Hanzei, and becomes the 19th emperor of Japan.

• Rabbula becomes bishop of Edessa.
• The Councils of Carthage are held, on the issue of Donatism.

• Merovech, Founder of the Merovingian dynasty and grandfather of Clovis I (approximate date)

• September 18 – Constantine III, Roman usurper
• Constans II, usurper and son of Constantine III
• Gerontius, Roman general
• Gundomar I, king of Burgundy
• Yax Nuun Ayiin I, king of Tikal (Guatemala) (approximate date)