When we talk about the truly 'great' comic books to have graced the medium, typically it's in reference to the many storylines and collected editions that take into account more than one issue. Every now and then, however, an issue comes along that accomplishes what most arcs do in six issues in but one, providing a 'one and done' story that's both accessible and definitive in equal measure.
They're few and far between, and though some do set up the rest of an arc, they're no less impressive - even if these kinds of issues are something of a rarity these days.
An issue doesn't necessarily have to even be definitive to be considered one of the all time greats, with stories in both the superhero genre and elsewhere having enhanced previous material, or even reappraised it entirely, resonating not just because of their influence, but because they responded to an industry - and world - that's constantly changing.
With comics that have started years-long runs, defined them, capped them off altogether or even emerged out of the blue with little follow-up, here are the issues every comic fan should make a priority of seeking out.