Mastema is an angel who persecutes evil in Hebrew folklore. He carries out punishments for God. He tempts humans and tests their faith. He asked God to permit him to have demons as his subordinates. In the Zadokite Fragments and the Dead Sea Scrolls, he is the angel of disaster, the father of all evil, and a flatterer of God. His name is that of an arch-demon who first appears in the literature of Israel's Second Temple Period, as a personification of the Hebrew word "mastemah" (משטמה), meaning "hatred", "hostility", "enmity" or "persecution".

From Hosea 9.7-8:

7 The days of punishment are coming, the days of reckoning are at hand. Let Israel know this. Because your sins are so many and your hostility so great, the prophet is considered a fool, the inspired man a maniac. 8 The prophet, along with my God, is the watchman over Ephraim, yet snares await him on all his paths, and hostility in the house of his God.

According to the book of Jubilees, Mastema "Hostility" is the chief of the demons engendered by the fallen Watchers/Angels with women, perhaps one of those same demons.