Last night, after almost 15 years and 140 episodes, the animated sci-fi comedy Futurama aired its series finale — for the fourth time.

Few shows in history have had the string of unlikely cancellations and revivals that have greeted this cultishly adored series. Futurama originally aired on Fox from 1999 to 2003. In the wake of its cancellation, the show's syndicated ratings and DVD sales proved strong enough for Fox to greenlight a revival in four direct-to-DVD movies — and that was successful enough to spawn a fully revived series on Comedy Central, where it ran for two more seasons.

So is this really the end of the road? In June, star Billy West told me he still thinks it's likely Futurama will be revived again in one form or another; earlier this week, creator David X. Cohen told The AV Club that he thinks Futurama is over for good. We'll see what happens in the months to come — but if last night's "Meanwhile" is the true ending of the series, it's a smart and poignant grace note to go out on.

Then again, one could say that about any of Futurama's previous "series finales." There's a kind of uniformity to Futurama's finales; all four center on Fry and Leela's relationship, and all four were written by executive producer Ken Keeler, who's long been one of the show's most reliable writers. Looking over the show's long history of possible endings, how do they stack up? Here, we evaluate the four "series finales" of Futurama:

4. "Overclockwise"
September 1, 2011

When Comedy Central renewed Futurama for a sixth season in 2009, it wasn't immediately clear whether the show would also return for a seventh. That's why the creative team conceived "Overclockwise" as a possible series finale. It's a solid but unspectacular episode, noteworthy mainly for its unique focus on Bender and for its sweet ending.

In "Overclockwise," Cubert reprograms Bender and dramatically increases his processing power, which eventually renders him so powerful that he develops omnipotence. When he returns to normal at the episode's end, he reveals that he took the time to write down the answers to life's greatest questions — a list that apparently includes the future of Fry and Leela's relationship. As the pair browse a summary of the rest of their lives together, we only see their reactions: Shock, laughter, anger, a sentimental tear. The episode ends with the two looking warmly at each other, reassuring fans that whatever bumps lie ahead for them, Fry and Leela are together for the long haul.

3. "Into the Wild Green Yonder"
February 24, 2009

The four direct-to-DVD movies that served as Futurama's first post-Fox revival tell four longer, self-contained stories — but in case it turned out to be the final ending of the series, the show's creative team designed the ending of the final movie, Into the Wild Green Yonder, to serve as an ending for Futurama as a whole.

In the wake of the movie's galaxy-shaking events, the show's sprawling ensemble cast is being chased through space by Zapp Brannigan. As the ship drifts into a wormhole — which the Professor says could transport them trillions of miles away from Earth — Fry and Leela profess their love for each other and kiss for the first time. It's a lovely, wide-open ending that gives the entire cast a strong sendoff, and Fry and Leela a final moment together — even if all that limitless potential was largely (and necessarily) undone by the revived premiere episode, "Rebirth," on Comedy Central.

2. "Meanwhile"
September 4, 2013

If Futurama really is over for good, last night's "Meanwhile" was a strong episode to go out on. Like several of Futurama's all-time great episodes, "Meanwhile" relies on time travel — but instead of going back years, the Professor invents a device that allows people to go back just 10 seconds. Though Fry originally plans to use the device to extend his marriage proposal to Leela, he ends up breaking it — which freezes everything in the world except Fry and Leela.

From there, the episode time-lapses through the rest of their lives together, exploring the world in each other's company as they spend their remaining decades walking across oceans and continents together. But when they return, in old age, to the place where Fry originally planned to propose, the Professor appears and offers them the chance to go back in time again. When Fry asks if Leela wants to do it all over again with him, she says "I do," and the three disappear together.

It's unclear exactly how far back they're going; the Professor says it's to when he "conceived" the time travel device, which could be anytime from the beginning of the episode to the beginning of the series. But immediately after the finale, Comedy Central aired the show's pilot, which seems to imply that Futurama's entire timeline was reset again — an ingenious and appropriately sci-fi way to ensure that even in cancellation, Futurama's story is never really over.

1. "The Devil's Hands Are Idle Playthings"
August 10, 2003

"Meanwhile" is a near-perfect send-off for Futurama — but it doesn't quite top the finale Futurama got more than a decade ago. Futurama's first series finale is still its best, demonstrating the show's deft balance of absurdist, gag-heavy comedy and unexpected poignancy.

"The Devil's Hands Are Idle Playthings" is a madcap episode that sees Fry making a deal with the Robot Devil to gain the musical talent he's convinced will finally win Leela over. When Fry becomes a world-class holophonor player, he composes an opera that sums up her life and his feelings for her — not realizing that the Robot Devil has launched an elaborate plan to take Leela as his own wife.

The gleefully absurdist episode is littered with callbacks to the show's original four-season run, from the holophonor Fry first used in "Parasites Lost" to the re-emergence of the always-welcome Robot Devil (Dan Castellaneta, delivering the best guest vocal performance in the series' run). The climax of the episode offers the show's all-time best musical number, as the sprawling ensemble cast chimes in on the big operatic finale.

But it's the episode's poignant final moments that make the strongest impression. Fry gives up his musical talents to save Leela, and the show tweaks the unbearably precious cliche about the music being in Fry's heart all along — he really is terrible without the Robot Devil's help. But as the rest of the crowd vacates the arena, Leela stays behind to watch him fumble through the final notes, saying, "Please don't stop playing, Fry. I want to hear how it ends."