Daidou Katsumi is a major antagonist in the tokusatsu series Kamen Rider W. He transforms into Kamen Rider Eternal, a powerful and ruthless Dopant hunter. As the leader of NEVER, a group of undead soldiers, Katsumi seeks revenge against the world due to his tragic past and the experiments that turned him into a superhuman. His complex motives and charismatic presence make him a memorable villain who challenges the protagonists both physically and psychologically.