DC is having an “DC Comics Events” digital comics sale, which is eclectic, to say the least. Let’s hit the highlights.
At DC, “Event” frequently means “Crisis,” so here’s the Crisis lineup – Crisis on Infinite Earths, Identity Crisis,Identity Crisis, and Final Crisis. A few comments on the set, the classic “Crisis” trilogy is Infinite Earths / Infinite Crisis / Final Crisis. Identity Crisis was more cashing in on the name and comes with it’s own set of baggage. (I will say that the first issue of Heroes in Crisis did have a little bit of an Identity Crisis vibe when I read it, so I see where the pre-publication comments were coming from.) This edition of Final Crisis should contain the two Superman Beyond issues that you absolutely need for the full story.
There’s a LOT of Batman in here. Batman’s been somewhat event-driven since the 90s. You can dig through the overall sales link to pick your period, because they’re all represented, but I’ll pick No Man’s Land for the highlight. Gotham is cordoned off after an earthquake and its ruins are divided up into feudal fiefdoms by the ex-pats of Arkham Asylum and a gang war rages as Batman and company plot to take back the city.
Green Lantern’s been an increasingly Event-driven title in recent years. The first real Event was what I’d consider the peak of the Geoff Johns Green Lantern era: The Sinestro Corps War. I’d need to ponder for awhile, but that might be my favorite Johns work.
But if you want to go OLD SCHOOL, the original reoccurring Event in the DC universe was the annual Justice League / Justice Society team-up. These are collected under the title Crisis on Multiple Earths (Volumes 1, 2, 3, 4, 5 and 6.) All good stuff, but if you were going to be picky, I’d narrow it down to Volume 6 (the Ultra-Humanite’s Crime Syndicate arc and a time travel caper that crosses over with All-Star Squadron), Volume 5 (for the influential New Gods crossover that was key in establishing Darkseid as a big bad post-Kirby) and Volume 3 (for the Seven Soldier of Victory arc, but CW fans might also be interested in the Earth X arc).
And for something a little different, there’s Hawkworld, Tim Truman’s post-Crisis treatment of Hawkman as a Thanagarian cop.