Professor Xavier dies – Professor Xavier died in issue 11 of the much-hyped "Avengers vs. X-Men" miniseries in 2012, an event that sent ripples throughout the X-universe.
Same sex wedding an 'X-Men' first – Northstar popped the question in "Astonishing X-Men" #50, and he got married the following month.
Superman and Wonder Woman, together – It's been a topic of fan conversation for decades, but it finally happened in 2012: Superman hooked up with Wonder Woman. The current version of Superman has yet to date Lois Lane. He's trying to make it work with the Amazon princess.
Buffy's choice – On television and in comics, "Buffy the Vampire Slayer" has pushed boundaries. "Buffy the Vampire Slayer: Season Nine" dealt with abortion, a rarely discussed topic in comics. Two 2012 issues featured a story in which the slayer decided to terminate a pregnancy.
Superman renounces his citizenship – In 2011, Superman decided he would no longer be a citizen of the United States after his attempts to settle conflicts in the Middle East got him in hot water with the government. It was a big deal for the onetime protector of "truth, justice and the American way."
Captain America dies – The death of Captain America by an assassin's bullet in 2007 (and his inevitable return in 2008) were seen as a reflection of the times and the United States' place in the world.