Superman #669

Superman and Supergirl fly side by side alongside Krypto the Super-Dog, while a glowing white silhouette — the mystery figure of the cover's central question, "Who Is the Third Kryptonian?" — hovers enigmatically above them, all set against the looming, cold-eyed face of a cybernetic villain. Jesús Merino's cover does a fine job building intrigue around that blank, unnamed presence while grounding the image in the warmth of Krypton's most familiar heroes. With Kurt Busiek writing and Rick Leonardi penciling, this 2007 chapter of the "Third Kryptonian" arc promises an engaging puzzle at the heart of Superman's world.