Zartan...
What can be said about him? Nothing.
Why? Because no one knows who he really is. In fact, Psyche Out believes that Zartan himself may no longer know who he is. What little we know is all based on our best assumptions. Yes, we're guessing.
We think he started out as a small-time hood with a penchant for disguises. This may have led him to study makeup, both traditional and special effects. This, in turn, led to his mastery of it. At some point, he mastered voice manipulation. He used his talents to commit crimes and became the de-facto leader of the Dreadnok biker gang. They still maintained a President and upper echelon however, they were always at the ready for Zartan's call. Somewhere along the way, he came into contact with Cobra and began taking on small jobs for them, breaking and entering leading up to full-fledged espionage and ultimately assassination.
Zartan began incorporating advanced technology into his repertoire including a highly advanced stealth technology that allows him to seemingly disappear into thin air. Considering no one has ever come forward claiming to have lost it and we have yet to see anyone, including Stark, use anything even half as sophisticated and successful, we can only assume whatever party he took it from wishes to remain anonymous.
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Inspired by the great work of Stronox