Detective Comics #239

From January 1957, this issue of Detective Comics presents a genuinely unsettling scenario right on its cover: two Batmen face off in what appears to be a cave, fists raised, while Robin looks on from the stairs behind them — one of those Batmen is a robot duplicate who taunts his human counterpart with the chilling boast that their minds are "exactly alike." Sheldon Moldoff's cover art captures the tension with clarity, making it instantly clear why the story is teased as "Batman's Robot Twin!" This is Silver Age DC storytelling at its imaginative best, pairing a fun sci-fi premise with the kind of eye-catching cover that made Detective Comics a newsstand standout in 1957.