Mr. Freeze
Mr. Freeze was portrayed by George Sanders in season 1, but Sanders was unavailable to reprise the role. As a result, Otto Preminger was cast to portray Mr. Freeze in season 2, where Mr. Freeze was going to appear in 4 episodes. Due to tensions and difficulties on set in Preminger's two-part storyline, Eli Wallach replaced Preminger in the role of Mr. Freeze for the final two-part storyline of season 2.