Lost up to Season 3.
BSG up to the end of the series.
Babylon 5 up to the end of the series.
The 2009 Star Trek movie.
The Star Wars prequel trilogy and Clone Wars animated series.
An interesting phenomenon that has developed in the last ten years is the idea of 'multimedia storytelling', of conveying a narrative using more than just one medium. So you may be able to watch a movie by itself, but have you read the tie-in comics that set up the movie's storyline and fill in a couple of puzzling apparent plot holes? And when your favourite TV show ends after five seasons of building up a densely-plotted mythology only to leave a couple of unresolved questions, you can be sure a spin-off novel, comic or TV movie is coming along to fill that gap.
Back in the good old days, there seemed to be a golden rule: the TV show or movie is canon and everything else is filler. All those racks of Star Trek novels released by Pocket Books in the 1980s and 1990s? They never happened. The Doctor Who New Adventures books which kept the torch burning for fifteen years whilst the show was off the air? They never happened either (although the current TV writers remade one of them as an episode, confusing fans about whether they are canon or not).
Thanks to the books, Lucas never got to use his original name for the Republic capital, Banafeepdingadong, world of the lemming-eskimos.
But then things started changing. It's difficult to pinpoint where it started. For many, it was when George Lucas started using elements from the comics and novels whilst writing the Star Wars prequels. 'Coruscant', the Republic/Imperial capital, was first named by Timothy Zahn in the 1991 novel Heir to the Empire, and fan pressure encouraged Lucas to keep the name in The Phantom Menace. At some point Lucas took the decision that not only the books and movies were canon, but so were the computer games, old 1980s cartoon series and the roleplaying game material, creating a vast and complex web of material. Whilst now somewhat daunting for the newcomer, it nevertheless adds something to the universe when you know that the major movie character death in Vector Prime was personally sanctioned and approved as canon by George Lucas himself.
You don't need to read it, but it's pretty good. And narrated by Londo. Whilst drunk. And is therefore fantastic.
One of the first true multimedia productions was Babylon 5. Creator/producer/head writer J. Michael Straczynski was aware that people were bored of reading books which were immediately rendered worthless by the TV series. Peter David's Star Trek: The Next Generation novel Vendetta may be the greatest ST:TNG story ever told, but in the context of the series it never happened, which is irritating for fans of that book. So JMS made a decision that everything published under the Babylon 5 name would be canon. He even decided that elements in the books and comics would be referred to by the TV show just as validly as an event in a prior episode. Whilst in the end this idea was scaled back from its original extent, it was still important. The reasons for Commander Sinclair's removal from B5 and transfer to Minbar at the start of Season 2 were given verbally in the Season 2 premiere and not a lot of time was spent on it, but a four-issue comic mini-series expanded on this story in much greater depth. One of the Minbari characters that appears in this arc, Rathenn, later appeared on the show itself. Another comic story showed Garibaldi and Sinclair crashing on Mars in 2253 and seeing humans and servants of the Shadows collaborating on excavating a Shadow ship, a full year before the same events were shown in the TV episode Messages from Earth. Garibaldi even gives a brief potted summary of the comic story on-screen, which may be a first for an American SF live-action TV show.
Far greater in scope, for fans, was when the series ended and several loose ends were left dangling, most notably the story of the Drakh orchestrating events on Centauri Prime in secret and the story of the growing telepath crisis on Earth. The former story was to some extent resolved in flash-forwards scenes in the series itself, but we never got to see how the characters got from 'A' to 'B' in that instance. Peter David stepped in and gave us the Legions of Fire novel trilogy, which filled in the gaps, hit all the necessary references and managed to be pretty damn entertaining as it went. Similarly, the telepath storyline was resolved by Greg Keyes in his Psi Corps trilogy, which again did its job pretty well.
However, these examples are interesting because whilst those books and comics fleshed out the missing links in the show, they are arguably not themselves necessary to understand the series. If you just watch Babylon 5 on DVD, there is enough closure by the final episode not to feel that you have missed anything important. The Centauri Prime books show how Londo got from where we saw him last in the 'present' in the series to his final appearance in the flash-forwards in the TV movies and earlier episodes, but they are not critical to an understanding of the end of that story. Babylon 5 treaded a very fine line there but was generally successful in doing multimedia storytelling well.
Other franchises have had more mixed fortunes. A recent high-profile example is Revenge of the Sith, in which we meet General Grievous, a robot with asthma. Erm, why does the robot have asthma? And how did he kidnap the Chancellor of the Republic from its presumably heavily-guarded capital world? The opening of the movie is a bit confusing in this regard and no wonder: all of this stuff is actually explained in-depth in the final episode of The Clone Wars animated series (Mace Windu wounded Grievous in battle, giving him his respiratory problems). This is a wobble in the idea of multimedia storytelling and leans towards the biggest problem in the idea: that part of the audience will miss the secondary medium in which a vital part of the story is being told and will wind up confused. Sith just about gets away with it as, in the grand scheme of things, Grievous isn't the real villain of the piece and the focus of the movie's story is elsewhere.
Something which screwed up a bit more royally in this area is Lost. Throughout Season 1 eagle-eyed fans had noticed the same numbers cropping up again and again in the background. In a revelatory moment, one of the key characters, Hugo, is revealed to have been haunted by these numbers ever since he used them to win the lottery. Later episodes and the main storyline of Season 2 also hinged on these numbers. The numbers were a big deal, one of the primary mysteries of the show, and an explanation for the origin and nature of these numbers would obviously be a big revelatory moment in the show's history.
Except that the explanation instead was instead given in a between-seasons Alternate Reality Game (ARG). This left a lot of fans nonplussed, for not only was this key explanation given outside the TV show, but it wasn't even in a relatively-easy-to-find comic book or novel, but in a fairly obscure internet-based puzzle game (a sort of follow-the-clues game spanning dozens of different websites and fairly intricate and time-consuming in nature). The game's plot was confirmed by the producers to be canon (and reiterated fairly recently in Season 5 interviews as well), leading to bemusement on behalf of the fanbase. This was a key story in the show, or at least presented as such, and it was resolved in a manner that left out 99.9% of the fans? Very strange. Once the ARG was concluded, the numbers' prominence in the show diminished sharply (they only play a brief role in one scene of one episode of Season 5, for example), although they would continue to randomly crop up in the background. This was a good example of how not to handle the multi-media approach to storytelling. Even today fans continually ask, "So what were the numbers about?" and when told where the answers are a usual response is, "They didn't answer it in the show itself but on some website? Lame."
This year we have seen three big-budget blockbuster movies hit the screen, Watchmen, Star Trek and Transformers: Revenge of the Fallen. In each case, the movie was accompanied by multi-media accompiament. Watchmen had a spin-off animated DVD (Tales of the Black Freighter) and a fictional documentary (Under the Hood) released to accompany it, although in these cases this was purely complimentary material delving a little bit more into the background of the film's universe. The other two cases were more problematic.
Transformers built on story elements established in the movie spin-off comic books that had been published between the two films, and several key story points outlined in the comics set up the movie with no reference in the film itself. Of course, since the movie's storyline was a chaotic mess designed purely to emphasise explosions and Megan Fox, this is not a major problem.
Star Trek, on the other hand, was altogether more riddled with noticeable plot holes, mainly due to its more linear and clear-cut storyline. So what the hell is 'red matter'? How do simple Romulan miners have a ship which can annihilate 50 Klingon battlecruisers (no matter how antiquated) in ten minutes? What impact did Spock's disappearance and the destruction of Romulus have on the original timeline? Is the original timeline still even there? Again, all of these questions were answered (and, for the most part, reasonably well) in the associated comic book launched a couple of months before the movie aired.
"It explains that the BSG story is a recursive story of tragedy and self-destruction unfolding across four thousand years." "Interesting. How do we depict that on the cover?" "Blond girl, in her underwear, all chained up?" "SOLD."
Battlestar Galactica, interestingly, was never one for multimedia storytelling during its run. 'Webisodes' were used prior to Seasons 3 and 4.5 to tell other stories, but these were just treated as small, mini-episodes designed to illuminate certain plot points rather than a radically different method for telling stories. The novels and comics are noticeably regarded as non-canon by the writers and studio. However, as Season 4 developed, one of the show's writers, Seamus Kevin Fahey, decided it might be interesting to develop a comic mini-series exploring the backstory of Kobol, Pythia, the Thirteenth Tribe, Earth and the Final Five in greater detail and went to work on this project, using the production staff's discussions in the writer's room as a guideline. By the time the much-delayed comics were released, there had been some changes in the writing of the actual series to mean that there were some minor inconsistencies (and one big one) between the comic and the series, but both the Sci-Fi Channel (or SyFy as it now is) and BSG producer Jane Espenson (who is taking over from Ronald D. Moore as the producer-in-chief of all things BSG-related in a few months) consider The Final Five comic to be canon, or as close to a canonical explanation as the audience is ever going to get for not just those elements mentioned earlier, but also the mysteries of the Head-Beings and Starbuck's return. Given the utter fury that was unleashed by some segments of the fanbase when BSG's final episode aired and those elements weren't even really addressed, let alone explained, it's interesting that a quasi-canon explanation now exists, albeit in a different medium.
Skimming the service of these multimedia stories and how they've been handled so far, it's clear to see we're merely at the start of how these different mediums will be used to handle stories in the future. The message seems clear: supporting a film or a TV series with material in comics, computer games, websites and books is fine, but it should always be done in an optional manner. The way Babylon 5 handled it seems to be the desirable model. The way Lost handled it - dishing out a major TV storyline revelation in a medium where hardly anyone will see it - is to be avoided where possible to avoid cheesing off your audience. In fairness, the producers of Lost have said themselves this maybe wasn't the best idea every and in the future they want such story points to be revealed through the 'mothership', the primary medium of the story, rather than in side-materials.
It will be interesting to see where this style of storytelling goes in the future.