An energy being or astral being is a theoretical life form that is composed of energy rather than matter. They appear in myths/legends, paranormal/UFO accounts, and in various works of speculative fiction, also in some religions it's believed that there is a whole race of such creatures who live amongst humans and "satan" is a rogue one of them.
Energy beings are typically rendered as a translucent glowing fluid or as a collection of flames or electrical sparks or bolts; somewhat in common with the representations of ghosts.
Energy beings have a variety of capacities. The Taelons (from Earth: Final Conflict) are barely more powerful than mortals, while others such as Star Trek's Q, Stargate SG-1's Ascended Ancients/Ori, Ben 10: Alien Force's Anodites, or the Meekrob from Invader Zim possess god-like powers.