When did Daniel the prophet die?

Daniel the lead character of the Book of Daniel is not mentioned elsewhere in The Bible, and there is no record in history of his existence, even though the story says that he rose to become the second most powerful person in each of the Babylonian and Persian Empires.

The Book of Daniel, written approximately 147 BCE, is of little help. It says that Daniel was a young boy at the time of the Babylonian Exile, but the story concludes with Daniel still very much alive.