...if instead of Colonel Green, the 'villain' of Earth's past had been none other than Khan Noonien Singh? Not the real one, but an illusory one, taken from Kirk's mind, and played once again by Ricardo Montalban, natch. 
Personally, I think it would have resonated more with the audience, rather than being someone who has never developed any significance in the Trekverse other than on 'Enterprise' thirty-five years later. I only wonder if having it be Khan might have been distracting from the main plot?
Additionally, would someone other than Lincoln have been a better 'hero' choice?
For that matter, for those familiar with comics, what if this had been more like Marvel's 'Secret War' from the eighties? Various forces of good and evil, in this case, recreations of past and present, meeting to duke it out for the amusement of the Excalbians.
I'd be curious to hear everyone's 'wish list' of heroes and villains for this episode. Obviously each candidate should be someone who would have existed or have been in the history books in 1969, so no one from the later series. Would you tap previous 'guest villains' from the series to appear, or are there historical figures that you feel might have fit better?

Personally, I think it would have resonated more with the audience, rather than being someone who has never developed any significance in the Trekverse other than on 'Enterprise' thirty-five years later. I only wonder if having it be Khan might have been distracting from the main plot?
Additionally, would someone other than Lincoln have been a better 'hero' choice?
For that matter, for those familiar with comics, what if this had been more like Marvel's 'Secret War' from the eighties? Various forces of good and evil, in this case, recreations of past and present, meeting to duke it out for the amusement of the Excalbians.
I'd be curious to hear everyone's 'wish list' of heroes and villains for this episode. Obviously each candidate should be someone who would have existed or have been in the history books in 1969, so no one from the later series. Would you tap previous 'guest villains' from the series to appear, or are there historical figures that you feel might have fit better?