So with some trepidation, I'm entering this challenge and have decided to model your typical (in some ways) evil scientist bent on world domination and retribution.
I've also decided to take Dango's good advice and create a semblance of a back-story to round out my character that is only just beginning to form in my head.
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Having been mocked about his stature for years by his taller coworkers, the diminutive but brilliant Dr. Mel Ishis PhD. has finally turned on the Institute for Scientific Discoveries and Academic Thought for the Origins of Kinetics (I.S.D.A.T.O.K.) and its population of narrow-minded and petty scientists along with the whole planet by extension (and further pettiness). Using his background in kinetics, Dr. Mel Ishis has drawn up plans for an intelligent weapon with the capacity to destroy life as we know it (leaving, incidentally, the millions of uncharacterized organisms on earth virtually unscathed). Unbeknownst to all, in his aboveground lair, the evil doctor tinkers away with tungsten, neon, stainless steel, animal tissue, and used television sets. Finally, he steps back in awe (and so that he can see more than just the bottom of it). He has done it at last. Dr. Mel Ishis has determined the fate of our race; he has created...
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...well I'm not sure exactly what yet, so I'll leave you hanging there. Now I'm going to start some concept sketches. I'm thinking I'll be attempting a cartoony sort of style, mostly because I'm scared to try a realistic hominid.
Good luck to all the contestants!

PS I reserve the right to change my mind and create a completely different sort of villain should this idea fail me.