Year 351 (CCCLI) 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 Magnentius and Gaiso (or, less frequently, year 1104 Ab urbe condita). The denomination 351 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.

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• Princess Dowager Helan, mother of Wei Daowudi (d. 396)
• Li Gao, Chinese general of the state Western Liang (d. 417)

• September 28 – Flavius Romulus, Roman consul
• Marcellinus, Roman general (magister officiorum)
• Shi Zhi, Chinese prince and emperor of Later Zhao