Shadrach, Mesach, and Abednego replied to the king, “O Nebuchadnezzar, we do not need to defend ourselves before you in this matter. If we are thrown into the blazing furnace, the God we serve is able to save us from it, and he will rescue us from your hand, O king.”
Except for the episode quoted above, the book of Daniel deals with a character by that name. Apparently Daniel was a legendary figure in ancient times (like Noah or Job), a famous sage whose wisdom was reported across cultures. Did he ever really exist? Who can say? Besides, the point of the stories is more important— keep faith in difficult times.
The book of Daniel places Daniel living in Babylon and then Persia at the end of the exile in Babylon. It is a compilation of stories about him, visions attributed to him, and dreams he interpreted. It was probably put together around 165 B.C. since it (oddly) introduces the Seleucid king Antiochus IV Epiphanes, a cruel persecutor of the Jews who ruled in the second century. In a way all the stories of persecution in Babylon are really about the persecution by Antiochus. The book is meant to encourage the Israelites suffering at that time.
Daniel is written in apocalyptic style. This was a common form of literature in difficult times, giving people coded messages within the wild imagery to encourage their faith. Chapters 1-6 of Daniel are a cycle of stories about the sage Daniel defying and surviving persecution. He defies Babylonian requirements that Jews violate their law of keeping kosher but manages to stay an important figure at court by successfully interpreting the king’s dreams. The dreams themselves contain apocalyptic imagery— a hand without a body that writes on a wall, a statue, a special tree. Also in these stories three brothers survive being burned alive by depending on God (see above quote) and Daniel himself successfully navigates the lion’s den. Also in this section in Catholic and Orthodox Bibles are poetic additions— the Prayer of Azariah and the Song of the Three Brothers.
The next few chapters detail visions Daniel has, including visions of four beasts, of a ram and a goat, of 70 weeks, and of the king Antiochus IV Epiphanes and his eventual defeat by heavenly powers. The last part of Daniel has never been found except in Greek in the Septuagint. Thus only Catholics and Orthodox Christians accept this part as inspired by God. These chapters give us three more fantastic stories about Daniel (the first is about Daniel as a child). He reveals the evil plotting of two leaders against the righteous Susanna, proves the pagan god Bel to be a phony, and then defeats a dragon worshipped as a god (there is a final jaunt through the lion’s den too). The stories are meant to show the foolishness of pagan religion and (again) how to get through times of persecution. The book of Daniel also contains references to angels and the resurrection of the dead, suggesting the changing belief of the Israelites about the afterlife.