Skunk Kusai is one of Tezuka's less savory characters. He debuted in Astro Boy as a minor but noticeable villain, and played increasingly drastic roles over the course of Tezuka's writing. He went on to play villains in Lion Books, Black Jack, and Rainbow Parakeet, among others, and also played a number of important roles in animation, including both Metropolis and Marine Express, as well as the recent Astro Boy: Omega Factor for the Game Boy Advance. Like Richard Widmark, the American actor upon whom he was based, he is rarely part of the main cast of a series, but always important and memorable to an audience, sometimes even more so than the main villain of a given series.
(Source: tezukainenglish.com)