The cover theme game works like this: I'll show you three covers. They all have something in common, whether it be a character, a trait all three characters share, a connection between all three characters, a locale, a trait all three creators share, SOMEthing. And it isn't something obvious like "They all have prices!" "They all have logos!" "They all feature a man!" "They are all Avengers (who ISN'T?)!" "They're all dead (who HASN'T been killed off?)!" "They've all been cloned (who HASN'T been cloned?)!" "They're all mutants!" (who ISN'T a mutant?) "They're all orphans!" (who ISN'T an orphan?) "They're all legacy heroes" (who ISN'T a legacy hero nowadays?)! "They're all by the same artist!" (too obvious) etc.
In addition, please note that you must have some familiarity with comic book history to correctly guess these themes. You cannot guess the connective theme just by looking at the covers solely, you must have some knowledge beyond the covers. The connections will ONLY have to do with connections in the actual comic books (so no incidental connections like "they share the same last names of Vice Presidents," etc. Now, if the three characters were each named Gerald Ford, that'd be another story, as that'd no longer be incidental).
If you come up with an answer that works outside of what I intended, I'll give you credit (well, provided I think it fits, of course).
One more thing - if there are floating heads on the cover, ignore them! They don't mean anything! Same thing with corner boxes!
If you think you know the answer, e-mail me at firstname.lastname@example.org. Don't answer in the comments. This way, people who check in at different times of the day can still get credit for answering it correctly!
Here is an archive of all the past cover theme games, plus their answers. Before each new installment, I'll post the answers to the previous week's game.
Good luck and enjoy!
The X-Men always make things complicated because SO many things have happened to them, but I think that this is unique enough for you folks to see what I'm going for. The first two covers are admittedly a bit of an intentional "Hey, could the theme be...oh, no, the third cover doesn't work."