A Watcher is a type of biblical angel. The word occurs in both plural and singular forms in the Book of Daniel (2nd century BC), where reference is made to the holiness of the beings. The apocryphal Books of Enoch (2nd–1st centuries BC) refer to both good and bad Watchers, with a primary focus on the rebellious ones.
In the Book of Daniel 4:13, 17, 23 (ESV) there are three references to the class of "watcher, holy one" ("watcher", Aramaic ʿir; "holy one", Aramaic qaddish). The term is introduced by Nebuchadnezzar who says he saw "a watcher, a holy one come down (singular verb) from heaven." He describes how in his dream the watcher says that Nebuchadnezzar will eat grass and be mad and that this punishment is "by the decree of the watchers, the demand by the word of the holy ones" ... "the living may know that the Most High rules in the kingdom of men." After hearing the king's dream, Daniel considers for an hour and then responds:
And because the king saw a watcher, a holy one, coming down from heaven and saying, 'Chop down the tree and destroy it, but leave the stump of its roots in the earth, bound with a band of iron and bronze, in the tender grass of the field, and let him be wet with the dew of heaven, and let his portion be with the beasts of the field, till seven periods of time pass over him,' this is the interpretation, O king: It is a decree of the Most High, which has come upon my lord the king, that you shall be driven from among men, and your dwelling shall be with the beasts of the field. You shall be made to eat grass like an ox, and you shall be wet with the dew of heaven, and seven periods of time shall pass over you, till you know that the Most High rules the kingdom of men and gives it to whom He will.
Lutheran Protestant reformer Johann Wigand viewed the watcher in Nebuchadnezzar's dream as either God himself, or the Son of God. He promoted Trinitarian thinking by linking verse 17 ("This matter is by the decree of the watchers") with verse 24 ("this is the decree of the Most High").