As I look back at 2013, a recent entertainment highlight stands out, mostly discussed over on that other blog. The Day Of The Doctor, the 50th anniversary special for Doctor Who, brought together multiple Doctors and eras in a way the series is uniquely suited to.
But plenty of settings have a high enough Weird Level that you could cross several eras to call back a previous series in the same continuity.
Time travel would obviously make this easier, but there are other options as well, from visions of other times to suspended animation.
This idea was spurred on by this suggestion in a belated (and sweary) rant about the end of Star Trek: Enterprise, imagining a celebratory final story uniting all the series in the setting (and adding a new one, in the style of Peter Capaldi’s special guest eyebrows in Day). It would let them tie up the Temporal Cold War loose ends (and reveal who Future Guy actually was) as well.
Dark Horse’s Star Wars comics managed this without time travel in Vector, featuring a character introduced in the Old Republic era and placed in cryo-stasis for centuries - and prophecies and visions as well.
Immortal characters like vampires are obvious candidates to pop up long after their original starring roles. As I noted in my 30 Day Challenge, I’ve seen the same Vampire: The Masquerade character in games set in the 1940s, the 1990s and the 1970s, and he looked more out of place in the 70s than the 90s.
What about your games? What elements might pass from one to another, and allow PCs to meet their predecessors and successors?
Have your fantasy heroes trapped an ancient evil, and then the GM had it reappear in another game set centuries later? Could a warrior from a forgotten age return from the afterlife to save the modern adventurers battling his ancient enemy?