<P> Big O (ビッグオー, Biggu Ō) is the eponymous mecha of The Big O anime TV series, a black megadeus piloted by series protagonist Roger Smith . The robot was designed by series creator Keiichi Sato, who also designed the Mazinger mechas featured on the Mazinkaiser OVA and the mutant creatures of The SoulTaker TV series . </P> <P> Big O's design was the creators' way of creating something distinguishable from the Gundam franchise and the Real Robot series inspired by it . Instead of blocky body parts, Sato designed a mecha where the chest and hips were not separate from the rest of the body . That way, the giant's movement would seem sluggish, comparable to the giants of old tokusatsu shows, portrayed by actors in bulky, heavy costumes . According to Sato, the name "Big O" comes from the opening theme of Daitetsujin 17, "Oh! Giant Ironman". </P>

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