Who was the first Roman emperor known to wear a beard?

Hadrian is recognized as the first Roman emperor known to adopt the style of wearing a beard. This was significant as it marked a departure from the clean-shaven image that had been characteristic of earlier emperors like Augustus, Tiberius, and Nero, who preferred to present themselves in a traditionally Roman manner without facial hair.

Hadrian’s beard is often associated with his philosophical inclinations and his admiration for Greek culture, which valued the beard as a symbol of wisdom and maturity. This change in grooming style was also reflective of a broader trend in the Roman Empire during Hadrian's reign, where there was a growing appreciation for Hellenistic ideals and aesthetics.

In essence, Hadrian's choice to wear a beard distinguished him in the history of Roman leadership and influenced the appearance of subsequent emperors, making it a notable aspect of his reign.