Isaiah is a biblical 8th-century prophet who is most famous for being named after the Book of Isaiah in the Old Testament of the Bible. He is also reported to be one of the authors of the book.
In the book, Isaiah was alive during the reign of King Hezekiah. He made different prophecies about the nation of Israel such as its captivity by the Babylonians. He also predicted the birth of Jesus by a virgin and that Jesus would be executed and then rise from the dead to save all sinners.
While most scholars believe that Isaiah was a real-life, historical person, there is very little physical evidence to show that he existed.
The only evidence found so far (and even this is under debate) is the discovery of a clay impression called a bulla in 2015. The bulla is an inscribed clay or soft metal that is used for legal or commercial authentication. The clay impression that may have belonged to Isaiah was found in the Temple Mount in Jerusalem.
The partial clay seal showed most of Isaiah's name although there was damage to the seal and missing letters. The seal was found near another clay impression of King Hezekiah's name.
The fact that Isaiah's seal was found near Hezekiah's seal fit with the timeline and period and supported the biblical version that Isaiah lived during the reign of Hezekiah.
Biblical scholars believe that the seal is the first archaeological evidence of the prophet Isaiah outside of the writings in the Bible. However, other scholars remain skeptical because of the missing letters in the seal.