 In the interest of transatlantic appeal , it was decided that the main characters would be mostly American and therefore actors capable of producing an appropriate accent were used . British , Canadian and Australian actors formed most of the voice cast ; the only American involved was stage actor David Holliday , who was noticed in London 's West End and given the part of Virgil Tracy . Following the completion of the first series , Holliday returned to the US . The character was voiced by English @-@ Canadian actor Jeremy <unk> for Series Two . 
