 Gough and Millar had always wanted Marsters for the role of Milton Fine / Brainiac . The pair wrote a draft for the major story arc of season five , knowing they wanted a new villain on the show to fight Clark . With the arrival of the black ship at the end of season four , Gough and Millar decided to introduce Brainiac . To them , Marsters was the only actor they could envision that could fit the " menace , intelligence , and sexiness " Brainiac was going to embody . Had Marsters declined the role , Gough and Millar would have rethought introducing Brainiac , as they could not think of any other actor who could fill those shoes . Marsters felt excited playing a character that was completely intentional ; he likened the intention to that of a shark . As Marsters explains , " [ Fine ] was just composed of his intent . And that 's exciting — it 's like watching a shark . You don 't really ask how a shark is feeling — it 's pure . " 
