If “parasite” and “entity” aren’t buzz words with a lot of associations in your mind, it’d probably be easier to describe Parallax as the god of fear in the DC universe’s cosmology. If you’re afraid of something or, more importantly, if you have the power to instill great terror in others, then you fall under this insect-like creature’s domain. Likewise, if the Green Lantern Corps is all about having the willpower to overcome emotions like fear, it fits that Parallax’s yellow-themed Sinestro Corps would be their antithesis, doesn’t it?
Think about your basic human emotions: they more-or-less boil down to anger, love, greed, compassion, hope and, yes, fear. In the DC universe, each of these feelings are personified by color-coded creatures (entities) who form an abstract, elemental pantheon called the Emotional Spectrum. Each entity has an accompanying order who draws power from it and works to spread its particular emotion throughout the galaxy. For example, the Red Lantern Corps serves the bull-like entity Butcher and fosters rage in the galaxy while the Green Lanterns serve the whale-like entity, Ion, who promotes the calm, stoic balance and control of emotions through willpower. Fitting right into that schema is Parallax and its Sinestro Corps.
Incorporeal deities typically have a desire to be incarnated in the material world (usually through the means of possession.) Out of all the entities, Parallax might have the most enthusiastic penchant for such parasitism. It possessed Hal Jordan, the greatest Green Lantern, after the destruction of Coast City, his hometown, decimated his willpower and left him terribly vulnerable to fear. The entity used him as a puppet for a terrible coup against the servants of its opposite number, the Ion, by compelling Jordan to kill almost all his fellow Lanterns and then seize the power within Oa’s great battery.== TEASER ==
As an avatar of Parallax, Jordan became a huge player in the DC universe's affairs for the next few years. With control oscillating between himself and the entity, he villainously attempted to reshape history to his own design in ZERO HOUR, then altruistically offered his own life to re-ignite the Sun during THE FINAL NIGHT. It wasn’t until Jordan became host to another being, the Spectre, that this parasite was finally exorcised from him. Since then, Parallax has taken home in the Sinestro Corps’ own power battery and has briefly possessed Jordan’s successor, Kyle Rayner, and best friend, Barry Allen. It’s currently being used by Krona along with all the other entities for a scheme in the WAR OF THE GREEN LANTERNS storyline.
It should be noted that Parallax’s history and true nature were devised as “retroactive continuity." Originally, Parallax was simply a new persona Hal Jordan took on after he renounced his Green Lantern identity. This “heel turn” storyline was tremendously controversial, however, so later issues revealed new details that could bring Jordan back to the side of angels without invalidating anything that had happeed. Thus, Parallax was re-interpreted as a parasitic entity that had been imprisoned in the great Oan battery by the Guardians for thousands of years. This was the “yellow impurity” which's presence in the core explained why Lanterns’ power rings didn’t work on anything of that color.
Parallax is set to be the main villain in the forthcoming GREEN LANTERN movie and it looks like the creature's been altered some. Instead of being an insect-like parasite, the entity better resembles a cloud of agonized souls. However, it still brandishes the inverted lantern symbol, it still wields yellow fear-based energies and, while it doesn’t look like it’ll be possessing Jordan, it seems like it’ll be using Hector Hammond as a host instead.
Most importantly, it stills look quite scary,