This "The Book of Knowledge." In this feature, I spotlight instances where notable revelations that affect comic book continuity were first made in texts outside of comic book stories themselves. In other words, times when stuff like the Official Handbook of the Marvel Universe either introduced or resolved changes to continuity.

Today, we look at how the Guardians of the Galaxy and Killraven were revealed to be the same Earth.

The Guardians of the Galaxy debuted first, in 1968's Marvel Super-Heroes #18 (by Arnold Drake and Gene Colan), as a team put together to deal with the fact that the evil Badoon have conquered the entire Milky Way Galaxy and so a few survivors from the various colonized worlds of the Milky Way teamed up to take the Badoon down.

In Jim Valentino's Guardians of the Galaxy #1 in 1990, he gave a nice summary of their history (it is pretty funny that there was a time when the entire history of the Guardians of the Galaxy could realistically fit into a four-page recap)...

Five years after the Guardians made their debut, Killraven took his bow in Amazing Adventures #18 in 1973 by Roy Thomas, Gerry Conway, Neal Adams, Howard Chaykin and Frank Chiaramonte....

This was set in the distant future of 2017 and when we see the young warrior Killraven kill a scientist who had experimented on other humans, the dying scientist fills Killraven on what was going on on Earth, tying the story into the basic set-up for the series, which was a rough adaptation of HG Wells' War of the Worlds, with the Martians having invaded Earth...

So, Killraven's further adventures were like the Guardians, except instead of driving off the Badoon, he was trying to drive off the Badoon.

In Valentino's Guardians of the Galaxy #2, he established that the Martian invasions DID take place in the Guardians of the Galaxy continuity, which led to the creation of the Stark...

The tricky thing, though, with alternate realities is that how do you know if two books took place in the SAME reality, or if they just both took place in different realities that both happened to have Martian Invasions.

It's a tricky concept, but they officially established in Marvel's Official Handbook of the Marvel Universe: Alternate Universes 2005 that both Killraven and Guardians were in the SAME reality.

Guardians was now set on Earth-691 (the cover date of their debut was January 1969)...

and so was Killraven...

Thanks to Kevin Garcia for reminding me to note the impact of Valentino's Stark plot on the continuity decisions.

Okay, folks, this sort of thing is something that happens all the time, so if you have any suggestions for future "The Book of Knowledge" features, drop me a line at brianc@cbr.com!