Batman: A Death in the Family
December 2018 marked the 30th anniversary of the legendary Batman story arc A Death in the Family. The storyline featured one of the most innovative comic book marketing decisions of all-time. In a move that predated American Idol's phone voting and present day's social media voting contests, DC Comics decided to leave the fate of Batman's second Robin, Jason Todd, in the hands of their readers.
At the end of Batman #427, DC placed a massive ad that proclaimed the following in all-caps: "Robin will die because the Joker wants revenge, but you can prevent it with a telephone call.” The ad featured an illustration of Batman holding a badly injured Todd along with two phone numbers — one printed on each side of Batman's head.
The phone number on the left said: "The Joker fails and Robin lives." The phone number on the right said: "The Joker succeeds and Robin will not survive."