The Incredible Hulk #138

Herb Trimpe's cover for this April 1971 Marvel issue sets the stakes immediately: the Hulk crouches atop a rooftop ledge while the Sandman issues a chilling ultimatum — one more step and a young woman (identified inside as Betty Ross) plummets to the street below, where panicked onlookers and police watch helplessly. The tension practically leaps off the page, with the Hulk caught between his raw power and the cruel leverage of a hostage. Roy Thomas's story title, "Sincerely, the Sandman," promises a villain confident enough to sign his threats — and a Hulk with no easy way out.