In the original Greek usage, a daemon (Greek: δαίμων, romanized daímōn) was a type of lesser deity, divided into two categories: agathodaemons (good daemons) and cacodaemons (evil daemons).
The writers of the Christian New Testament used this word as a synonym for unclean spirits, and this is where the modern usage of the word "demon" comes from.
Design
Daemon's design was intended to appear simplistic. According to designer Masayuki Doi, the "coal black" skin and red hair were meant to emphasize their chaotic alignment. The pitchforks were chosen to oppose the Angels during cutscenes. Additionally, the Daemon's animations were purposefully made unpleasant and coarse to paint them as a "lowly demon minion."[1]
A low-ranking class of spirits. While the name may conjure up familiar images of "demons" due to Christianity's influence, daemons were not strictly associated with good or evil and simply thought to be lesser supernatural beings, sometimes acting as tutelary spirits that guided the souls of men. What might be considered a demon today would've been called a "cacodaemon" in ancient Greece—that is, an evil spirit. In contrast, their benevolent counterparts were known as "agathodaemons."