Endings to television shows are extremely tricky; writers are saddled with tying up the plot of the final season while also tying up the entire show, bringing back old characters without skimping on the new ones, concluding the thematic elements of the show without losing sight of the relationships and the overall satisfaction of the fans. And on top of all that, science fiction shows have to contend with explaining any mysterious mythology once and for all, and while some classic shows have risen to this challenge with aplomb, others have failed miserably. Here's our list of the best and worst sci-fi series finales, from barefoot balletic assassins to stone plugs for glowing pools of light:

Best: Firefly

Worst: Battlestar Galactica

Battlestar Galactica had set itself a tough task for its finale, with its web of complicated mythology and characters that were beloved precisely because they didn't fit into neat boxes. That's why it's so disappointing that the finale delivered the characters into such neat fates. Laura Roslin's overwrought dying sigh ("So… much… life!") was embarrassing. It was galling to see Head Baltar and Head Six getting in the last word by strolling off into the sunset condescendingly speculating on the fate of humanity. The Starbuck-as-angel concept, however, was what disappointed me the most. Starbuck was so utterly a representation of humanity in all its sexy, rumpled, mistake-making, desperate, brave glory. We wanted her smiling, but we didn't want to see her end up a self-satisfied apparition, vanishing while Lee is still talking like a total ghostly assh*le, no longer to share in the fate of the human race.

Best: Star Trek: The Next Generation

"All Good Things" won the 1995 Hugo Award for Best Dramatic Presentation, helped the show grab a rare sci-fi Emmy nomination for Best Drama Series, and is widely regarded as one of the best episodes of the series. It ends with the perfect final shot: the main cast playing their regular game of poker, reflecting on their futures, and Picard joining for the first time saying, "the sky's the limit." It was bittersweet, heartfelt, and a perfect valentine to the devoted fans.

Worst: Star Wars Clone Wars

It's not that the last episode of Clone Wars was bad per se, it's more that, as is the case with Firefly, we never got a satisfactory conclusion to the story arcs Dave Filoni and his team had been building. Over the course of the show, Ahsoka Tano had slowly grown from annoying brat to a powerful Jedi who had the guts to stand up for what she believed in. That we never got to see how her story ended is the most painful element of LucasFilm's cancellation of the show. At Star Wars Celebration earlier this year, Dave Filoni said he had added Clone Wars characters like Rex, Hondo and Ahsoka into Star Wars Rebels, not just for narrative purposes, but also to say thank you (and sorry) to fans of his first animated Star Wars show.

Best/Worst: Quantum Leap

It's tough to put Quantum Leap's controversial series finale in either the "best" or "worst" category, as your reaction to it may very well serve as a personality test. The ending was undeniably bleak, with Sam Beckett making a final leap to his friend's wife to inform her that he was dead, and then a quick postscript telling the audience that after five years of investing in his journey home, he never made it. Some have hailed the bittersweet ending as a perfect capper to an emotionally complex show, while others have written it off as disappointing and anticlimactic. For us, it depends on the day. At that same event, it was revealed that Filoni and his team had multiple seasons-worth of storylines mapped out for Clone Wars, but thanks to the Disney takeover, we'll never get to see them.

Worst: The X-Files

Similar to Lost, The X-Files had painted itself into a little bit of a corner with its increasingly complex mythology, making it nearly impossible to tie up every loose end. But it was still something of a letdown that so many questions went unanswered, and that Mulder and Scully were sidelined for much of the final episode. And then the kicker: the show ends with an imminent alien invasion- in ten years. Yes, they were setting up a future movie, but it was entirely anticlimactic. And considering the punishing reception of that film, it certainly wasn't worth ending the show on a feeble note.

Best: Dollhouse

Best/Worst: Terminator: Sarah Connor Chronicles





TSCC was a frustrating show, one that was often great but was also riddled with problems. Lena Heady was severely miscast as Sarah Connor, and the writers often took entirely uninteresting detours, like that stupid "three dots" subplot. But overall, it was a thoughtful, well-written show, with standout performances from Summer Glau and Brian Austin Green, and the end of the second season finally saw the show getting into a rhythm.



TSCC was a frustrating show, one that was often great but was also riddled with problems. Lena Heady was severely miscast as Sarah Connor, and the writers often took entirely uninteresting detours, like that stupid "three dots" subplot. But overall, it was a thoughtful, well-written show, with standout performances from Summer Glau and Brian Austin Green, and the end of the second season finally saw the show getting into a rhythm.





Case in point: the second season finale was an amazing hour of television, and opened many intriguing avenues for the show to explore in its third season. After floundering for two seasons in the pre-apocalypse, we were finally going to see the endgame of the Terminators, not to mention that Summer Glau was going to get to play both fan favorite Cameron and her human counterpart, Allison. It was a perfect season finale, which made it a terrible series finale, one that left fans desperately wanting more. Best: Babylon 5





An elegiac masterpiece, "Sleeping in Light" brought all of the themes in Babylon 5 full circle, all while servicing all of the most important characters and relationships. Rather than ending on a big confrontation or battle, Babylon 5 ends with a bittersweet last meal for Sheridan, where the destruction of Babylon 5 itself is almost an afterthought and tear-jerking, borderline manipulative moments reign supreme. This is one of the best series finales of all time, only narrowly beaten by the show at the top of this list. An elegiac masterpiece, "Sleeping in Light" brought all of the themes in Babylon 5 full circle, all while servicing all of the most important characters and relationships. Rather than ending on a big confrontation or battle, Babylon 5 ends with a bittersweet last meal for Sheridan, where the destruction of Babylon 5 itself is almost an afterthought and tear-jerking, borderline manipulative moments reign supreme. This is one of the best series finales of all time, only narrowly beaten by the show at the top of this list.

Dollhouse as a whole is understandably controversial among sci-fi fans, but there's no denying that its finale was wonderfully audacious. Where the series began with a more balanced attitude towards the personality-wiping technology at the show's center, the finale went full-on worst-case scenario and placed the characters in a post-apocalyptic landscape, quite literally demonstrating the logical end of humanity's need for wish fulfillment and tendency to objectify other people. There were some bumps here and there- the revelation of Boyd as the main villain was clearly part of Joss's five-year plan rather than a logical end to the two-season run- but overall it was a perfect example of a showrunner leaving it all on the field.