7. Amazing High Adventure #1-5
I'm going to say right up front that I haven't actually read these yet. Hey, you have to think outside the box sometimes. Actually, I haven't read them only because the shipment from ebay containing the whole run has gotten stuck in transit somewhere; I thought I would have it read by now, but them's the breaks.
But even without reading this series I'm still confident enough in it to put it in my top 12. Why? Well, honestly, I just love the fact that this series exists. Back when Marvel was willing to actually try new things (read: the early 80's), they put together this oversized, overpriced series of specials featuring some of the best creators in comics doing adventure stories. Not superheroes, but just straight up, Indiana Jones style pulp adventures mixed with dramatic stories set throughout history. Here are the CGD descriptions of the four stories from the first issue alone: "Pagan resistance to Oliver Cromwell," "Mayan resistance to Cortez," "time travel" and "Russian boy lost with dying Inuit man."
And then there are those creators. That story about Cromwell features art by John Severin, as does at least one story in almost every issue. Bill Sienkiewicz, Paul Smith, Mike Mignola, Val Mayerik, John Bolton and Steve Bissette are just some of the great artists who contributed to the series. How could you not want to read a story about "Napoleon's invasion of Egypt" drawn by Mike Mignola, or something simply described as "the early days of paleontology" drawn by Steve Bissette? I have a feeling Marvel won't be publishing any new comics about paleontology any time soon.
The first issue was published in 1983, with a second in 1984 and the third coming in 1985. They then made the series monthly, and it was almost immediately cancelled. I wish they had just left it as an annual, as it would have been nice to have Marvel's top talent continue to deliver a giant-sized book of adventures every year. But the fact that this series exists at all is enough for me.
Check out the credits on this one:

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