All month long we will feature brand-new Cool Avengers and X-Men Comic Book Moments in celebration of their fiftieth anniversaries this month. Here is an archive of all the past cool comic moments that I've featured so far over the years.

We finish out the Avengers side of the month with the debut of the first new Avengers lineup in Avengers #16 by Stan Lee, Jack Kirby and Dick Ayers!

It's hard to quite get across just how dramatic of a change it was at the time for Stan Lee to just abruptly replace the stars of the Avengers, all heroes who were starring in their own titles, with a relatively new supervillain, two former supervillains from the Brotherhood of Evil Mutants and just Captain America left over from the original team.

I love in this issue how Lee plays it like this is the most solemn transfer of power that you can think of, filled with pathos and high anticipation, all building to that first "Avengers Assemble" shout...

Very well done by all involved. It set a new standard for readers to truly never know what to expect in their comic books.