Miasma - a villainous and intelligent puff of toxic gas housed in a deadly 4-claw robot suit.
He is the main antagonist of 'Ripley the Reaper', an indie platforming game I was working on.
He wants to create an empire of pollution and toxicity where he would thrive, and so to get his hands on as many dead and decaying resources as possible, he invades The Underworld and tries to take it over.
One of my personal favourite character designs, however the game's development is postponed however indefinitely, so we might never get to se this guy in action. :(