Hexxus is one of the infamous Ancient Ones and a supporting antagonist in the Kingdom Hearts Unlimited Saga.
He serves as the primary villain of the Ferngully campaign in "The Fantasmic Dreamtime", having dragged his world of Ferngully from the Non-Disney Universe to the Realm of Sleep during the War against the Horned King.
There is one, true certainty in the universe: everything that has been created will, at some point or another, be destroyed.
Hexxus was born from the Primordial Chaos since the Age of Chaos, and has been around ever since the first living thing succumbed to mortality and died. His loyalties have usually shifted from the side of neutrality with Death ximself as his master, or to the side of evil with the Dark Lord Chernabog lording over him from the Realm of Darkness. One thing has never changed however: his hunger for destruction by any means.
As wars, disaster, and plagues ravage the land, Hexxus has always been there, rejoicing in the loss of life and the blighting of land. Being an Old One, Hexxus had the innate power to travel through time, and influence the course of history to always lead to the most destructive paths through which he would greatly benefit from.
While traveling through the endless seas of the timestream, the death god came to a far future in his timeline at the birth of the Industrial Revolution, when smoke was pumped into the air and oil was spilled into the seas. Hexxus was curious about this new means of destruction, and took on his permanent form of the Spirit of Pollution, manifesting as a humanoid figure composed of smoke or an oily skeleton.
He eventually gained enough destruction through pollution that he was able to become nearly unstoppable, and he immediately set a course back to his then current timeline in the past era of the Lands of Legend, where, using his newly gained Pollution Spirit forms, he wreaked havoc in the Aboriginal Dreamtime worlds in what would one day be known as Australia. Setting up a base for himself on the outskirts of the desert, Hexxus began conducting daily raids on the primitive rainforests where he rained down poison, destroying much in his wake and killing countless living creatures, including the primitive humans of that era. He was finally defeated by the Fae priestess Magi Lune and imprisoned inside an enchanted baobab tree, which he remained trapped in for hundreds, if not thousands or possibly even millions of years.
But Hexxus was far from done. As long as destruction continues, as long as death occurs, he will endure. He will not rest until the universe is reduced to ashes, and all living things are reduced to bones. Everything that has ever been created will, at some point or another, be destroyed. And Hexxus will be there to oversee it...just as soon as he gets out of that stinking tree first!
The Fantasmic Dreamtime
Appearance and Personality
Hexxus, true to all he embodies, could very much be considered the dark side of nature itself. At the core, he relishes destruction and decay. He also shows to take great pleasure in the suffering and death of living creatures. Hexxus (at least in his smoke form) usually talks in an extremely respectful and sensual fashion, and the pleasure he derives from pollution seems to be almost sexual in nature. However, he also shows great fear when the situation turns against him, such as when Zak turned off the leveler and then when he was imprisoned once again.
He is an exceptional manipulator, able to influence others from the shadows. Hexxus also seems to show some admiration for humans, describing them as "wonderful creatures, so clever and useful". Possibly because he and humans share much in common, they both cause destruction to nature and its creatures. Nevertheless, he only sees them as a means to an end and, like all other living creatures, Hexxus takes great pleasure in their deaths just the same. He also has shown overconfidence and enjoys taunting his prey; however, his own arrogance is ultimately his greatest flaw.
As the dark side of nature, Hexxus wields as variety of abilities and powers. He can change his form, which presumably depends on what type of poison or toxin he is currently feeding on, for example: Zak's spray paint (a shapeless blob of black ooze), the smog produced by the Leveler (a humanoid shadow of black smoke), the oil in the Leveler (a giant flaming skeleton-like beast draped in ooze like a cape), etc.
He has been shown to be able to mimic seemingly any voice. He is also able to breathe fire, both in his smoke and fire forms. His smoke form also appears able to cast bolts of acid. Hexxus can also possess machines, such as when he merges with the Leveler and also takes control of it once he scares off it's human operators. As stated by Magi Lune, Hexxus can rain down poison which presumably is his deadliest ability, for Magi states that during his first rampage the forest was "nearly destroyed and many lives were lost".
Aside from those abilities, Hexxus also seems to have some level of omniscience or omnipresence. Because as is hinted many times in his song "Toxic Love", it seems that, despite being imprisoned for countless years, Hexxus was still fully aware of how much humans and civilization had evolved over the millennia. Thus he, at least partially, understood the concept of machines, human greed, human work (shifts, breaks and all) and was aware of human things like shopping malls, cocktails, etc. Furthermore, he apparently also knew both the voice and even the personality of the lumberjacks' boss when he mimicked him over the intercom. The fact that he is a spirit further adds plausibility to this theory. Indeed, Hexxus himself has stated that he "sees the world and all the creatures in it".