In this feature we spotlight the various characters, phrases, objects or events that eventually became notable parts of comic lore. Not major stuff like “the first appearance of Superman,” but rather, “the first time someone said, ‘Avengers Assemble!’” or “the first appearance of Batman’s giant penny” or “the first appearance of Alfred Pennyworth” or “the first time Spider-Man’s face was shown half-Spidey/half-Peter.” Stuff like that. Here is an archive of all the When We First Met features so far! Check ‘em out!

This is a special mini-edition of When We First Met, answering a question I just got on Twitter from T_Campbell

Hey, do you know when the Avengers lead in "a day unlike any other" made its first appearance?

The answer is Avengers #128, from the summer of 1974.