Which emperor was captured by the Sassanid Persians and died in captivity? (r. 253-260 AD)

The story behind the answer

Valerian (r. 253–260) is the only Roman emperor ever captured alive by a foreign enemy. After his army was defeated by Shapur I of the Sassanid Empire at Edessa in 260, Valerian was taken prisoner and died in captivity—an unprecedented humiliation for Rome.

This happened during the Crisis of the Third Century, a tumultuous era of invasions, civil wars, and plague. The disaster crippled imperial prestige and left his son Gallienus to stabilize the core while breakaway states emerged. By contrast, Claudius II “Gothicus” defeated the Goths, Aurelian later reunified the empire, and Carus died mysteriously on a Persian campaign but was never captured. Memory tip: V for Valerian = Vanquished by the Sassanids at Edessa.