Allow me to fire the first salvo:
The first to question the authenticity of the book, would be the Neoplatonist philosopher Porphyry (ca. 232-303 CE). This is not surprising. He hated Christianity. Ironically, Daniel is a much maligned book today, but this time targeted by Christian Bible scholars. These would continue where Porphyry had left off. The reason: Most attempt to pin Daniel’s prophecies to events during the reign of Antiochus IV Epiphanes. These follow the interpretation found in the book of Maccabees, one that Jesus rejected outright (cf. 1 Maccabees 1:54, 59; Matt. 24:15, 16). Even the angel in Daniel’s final vision would doom a Jewish uprising, saying: “And the sons of the robbers [“violent ones”, CSBO] belonging to your people will, for their part, be carried along to try making a vision come true; and they will have to stumble”, i.e., die [1] (cf. Dan. 11:14b).
Modern scholars, with Porphyry, insist that there can be no predictive element in prophecy. By refusing to consider a post-Grecian interpretation of Daniel’s prophecies, these place an impossible burden on the interpreter as well as an insurmountable obstacle on the road to a satisfactory exegesis. These maintain that ancient wisdom cannot stand against the onslaught of modern criticism. No wonder the skeptics reign supreme. A similar situation existed in Asaph’s day: “Our signs we have not seen; there is no prophet any more, And there is no one with us knowing how long” (cf. Ps. 74:9).
[1] The Hebrew word for stumble is kâshal (= “to cause to fall”). Especially in the book of Daniel this verb refers to a literal stumbling because of war (cf. Dan. 11:33b). In most cases the Syriac interprets it as “to overthrow.” This fact is corroborated by HALOT: to fall, collapse (of a government, dynasty) Dan. 11:14, 19, 33, 35, 41. In each of these cases, the verb refers to people, not countries. The Maccabean dynasty, and all break-away groups, disobedient to God, would come to a violent end.