The fictional characters of The Big O anime series were designed by series creator Keiichi Sato, who also designed characters for the City Hunter series. Because of union rules, most of the English voice cast for the first season were credited under pseudonyms; the only ones who used their real names were Lia Sargent (R. Dorothy Wayneright), Wendee Lee (Angel), Michael McConnohie (Schwarzwald) and William Knight (Gordon Rosewater).

Source: Wikipedia