X2

The original cast and director returned for this second outing, and it brings forward the themes of mutants in a society that hates and fears them. This time around, the rogue Col. William Stryker is plotting to use the mutants' own technology and superpowers to track them all down and destroy them. The early scenes of Magneto in a plastic prison are striking and well-realized, and the attack on Xavier's school drives home how vulnerable our mutant heroes are in a world that hates them. The first X-Men movie was a bit rushed and formulaic with the need to introduce so many mutant heroes, but this one feels a bit more cohesive.

Back To The Future Part 2

Easily my favorite of the BTTF movies, this one actually takes us to the real future, instead of just 1985. Biff, the hapless bully, beats Marty at his own time-hacking game, creating an alternate timeline where Biff rules. I'm a sucker for any storyline where the hero has to cross his own timeline and run around the same series of events a second time, without upsetting all the applecarts he set in motion the first time around. Sure, it's goofy, but so was the first one.

Superman II

A confession: I haven't yet seen the "director's cut" that came out on DVD a couple years ago, because the idea of giving this movie the same ending as the first one seemed just patently silly. Famously, director Richard Donner had a falling out with the studio over this film, and the studio brought in someone else to finish this movie, and recut the final product. But I still really like the original cut, for its awesome mega-villains from Superman's own home planet, including General Zod. Of all the sequels to feature the hero giving up his powers to live a normal life, this is the most interesting, since Superman probably couldn't be with Lois otherwise. And I love the random yahoo in a bar beating the crap out of Clark. The only major flaw is the memory-erasing kiss at the end, which is total drek.

Robocop 2

This is another questionable one — but this film has a special place in my heart. Frank Miller's first foray into making movies, back when he was still an edgy maniac, picks up the satirical themes of the first movie and goes nuts with them. (Sure, the studio messed with Frank's script, but the result is still pleasingly freaktastic.) Detroit is being privatized, the police force is maneuvered into being on strike, and Robocop is out there on his own. We venture deeper into the dark heart of Robocop, as Alex Murphy tries and fails to recapture his original life with his family — and meanwhile, every attempt to create a new Robocop only leads to suicides (and murder-suicides) as the replacements can't face the horror of what they've become. Until OCP tries creating a totally amoral, power-crazed version.

Spider-Man 2

After reading the original Michael Chabon script for this movie, I marginally prefer that version — the whole "Peter Parker stops being Spider-Man" subplot in this movie is handled really weirdly and confusingly. (He suddenly needs glasses? Why?) But either version of the story is still a worthwhile continuation of the first film. Alfred Molina is a sympathetic but deranged Doc Octopus, and the sequence where Spidey stops a runaway train — and then the passengers don't rat out his identity — is a classic for a reason.

Daleks: Invasion Earth 2150 A.D.

The first Peter Cushing Dalek movie was a total flying-saucer wreck, with blond hippie aliens in blue eye-shadow and non-deadly Daleks. But this sequel, also based on an episode from the Doctor Who television series, is a total classic. It has much more energy, from beginning to end, and the Daleks are awesomely bloodthirsty. The supporting cast includes Bernard Cribbins and Philip Madoc, and the TV episode's slightly bloated plotline benefits a lot from being compressed down to a movie length.

Blade II

Guillermo del Toro stepped in and directed this sequel, instantly elevating it to a gothic horror masterpiece along the way. Blade, the "daywalker," is more enigmatic and cooler, and his relationship with Whistler takes a weird turn when he has to cure Whistler of vampirism. But mostly, this movie is memorable for its genetic engineering project, where the vampires are trying to breed a new race of super-vampires. Vampires + weird science = win.

The Chronicles Of Riddick

Thanks to Pansy for suggesting this one — it really should be on the list. Riddick, the merciless killer from Pitch Black, gets a whole backstory and and a heroic destiny, but mostly he kicks a whole lot more ass than in the first movie.

Dawn Of The Dead

Following on from the undead flesh-eating plague set up in Night Of The Living Dead, George Romero's second zombie film shows in more detail the effects of a widespread epidemic of reanimated cannibals. Containing one of the most famous shopping mall sequences in movie history, it's no accident that this is the Romero classic that Zack Snyder chose to remake. Thanks to Dr.Wadd for suggesting this one — although I think I can't quite get with Escape From L.A.

Mad Max: The Road Warrior

Many people probably didn't even know this was a sequel when it came out. The first Mad Max movie didn't make nearly as big an impact (in the United States, anyway) as this incredible follow-up, with its long scenes of caravan carnage. (It didn't help that when the original Max came out, Mel Gibson was dubbed with a horrendous American accent.) The original Max is a total classic, but movies like Doomsday are still biting the feeling of anarchy and vehicular mayhem that this sequel brings. Fans are still doing Road Warrior reconstructions on the public roads.

Aliens

James Cameron steps in and shows how to do a sequel to someone else's creation. Ripley goes back to the moon where she encountered the alien eggs, accompanied by a platoon of colonial marines. Every character in this film is an awesome archetype, from Burke the corporate weenie to Vasquez the tough marine chick. The supporting cast of this film is more memorable than the main characters of a lot of other films. (Even Newt, the cute kid, is tolerable.) From the moment they return to LV-426, the tension is palpable, and the action sequences only reinforce the feeling of a squad under siege in cramped quarters. By the time Ripley takes care of the alien queen using that power suit at the end, you're jumping up and cheering for her.

Terminator 2

Cameron already proved he had what it took to make a killer sequel when he returned to the film that put him on the map. In some ways, this is just a remake of the original, only with Arnie's Terminator in the role of protector instead of pursuer. But just like Cameron increased Ripley's bad-assery in Aliens, he does the same for Sarah Connor here, including her awesome mental institution escape. Having a reprogrammed Terminator — and actually getting to open up its head and change it from read-only to read-write — opens up all sorts of fascinating questions about the nature of artificial consciousness that the first movie barely touched on. All the cool ideas in Terminator: The Sarah Connor Chronicles get their start here.

The Dark Knight

I almost left this one off because of the constant debate over whether it really counts as science fiction... but still. This really is a primer in how to do a decent sequel. Batman Begins shows us the making of Batman, and the sequel comes close to showing us the breaking of him. Instead of another sequel where the hero randomly decides to walk away from being a hero in order to get married or have a "normal" life, this film shows us Bruce Wayne choosing to remain Batman in the face of almost unimaginable chaos that's laid at his door. Okay, he does almost reveal his identity at one point, but in the end, this film is a great continuation of the first movie because it shows just what it takes for Bruce to stay Batman. Thanks to all the commenters who insisted it should be in here.

Star Wars: The Empire Strikes Back

RoboCop 2 director Irvin Kerschner also directed another sequel, which might be slightly more famous. There's so much to love about this film, including our first meetings with Yoda and Lando Calrissian, and the way Darth Vader goes through Admirals like popcorn. But really, the reason why it's the best film in the series is because of the way it builds up to the revelation that Luke Skywalker's dad went bad — and there's an excellent chance that Luke will go the same way. The sequence in the cave, where Luke confronts his own inner darkness, is more powerful than everything Hayden Christensen ever committed to film.

Star Trek II: The Wrath Of Khan

And then, of course, there's the film that all other sequels are compared to. It doesn't hurt that the first movie in the series consists of three hours of watching a train pull out of a station, while people talk about grain futures. But still, this movie makes the original Trek characters as vivid as they've ever been, from Spock and McCoy both giving birthday presents to Kirk all the way up to the end. Almost every line of dialog in this movie has been in someone's sig file at some point, and this film does for space battles what Road Warrior does for car chases. And then there's Ricardo Montalban's magnetic turn as the obsessed, arrogant space maniac, Khan.

Starblazers. Desslok, leader of the Gamilons, tried to crush the puny humans over and over again, but finally lost his empire. So in season two, he decided to take revenge on the crew of the Yamato, who defeated his ambitions. He finally catches up to them in an episode auspiciously titled "Desslok's Victory," and pounds them with his gunships. Then he surrounds the Yamato with magnetic mines before the humans can fire their famous Wave Motion Gun. And then taunts his adversaries mercilessly. "Go on, take a shot." Ha ha ha ha. (I know it's sacrilege, but I actually prefer this scene in the English dubbed version.)

Battlestar Galactica. It takes less than an episode for things to go south between the Galactica and the newly discovered Battlestar Pegasus. Admiral Cain decides to execute the Chief and Helo, leading to a tense confrontation complete with the whirly cam. Commander Adama shows why you don't mess with Galactica, with his terse "I'm getting my men" speaking volumes. And then the phone comes down, because the space battle is on.

Star Trek II: Wrath of Khan. Star Trek pretty much perfected the art of hailing-frequencies bravado, as early as "Balance of Terror"'s Romulan Sub-Commander Tal. "Your ship is surrounded, Captain. You will surrender immediately, or we will destroy you." With Kirk responding, "Save your threats. If you board this ship, I'll blow it up. You'll gain nothing." But Trek's masterpiece of comm-taunting has to be TWoK, where Kirk keeps needling Khan's poor marksmanship, until finally he lures him into a disabling nebula by laughing at his superior intellect. "We tried it once your way, Khan. Are you game for a rematch?" The script says: "Khan's eyes bulge." And they do.

Serenity. This one's a bit different. Chiwetel Ejiofor's Operative is mournful and regretful after he slaughters dozens (maybe hundreds) of innocents to get to Mal. But he still needles Mal via the viewscreen, suggesting that all the carnage is Mal's fault. And he's successful in goading Mal to take rash action — just not maybe the action he was hoping for.

Avengers #94, part of the Kree-Skrull War saga. The Skrull emperor appears on a view screen to warn the Avengers that the Kree warrior, Mar-Vell, is creating the ultimate weapon, an Omni-Wave Projector. And then when the humans don't respond to his threats fast enough, the emperor launches Plan Delta, which sends an all-consuming fireball spiralling towards Earth.

Farscape, "Die Me, Dichotomy." In the second season cliffhanger, Scorpius takes over Crichton's brain via a neural chip, and the mind-controlled Crichton tricks Aeryn into letting him go. She chases after his module in her Prowler, leading to a harsh exchange. Scorpius asks her how the skull fracture is doing, and she threatens to shoot him down. "Make no mistake." Scorpius/John replies: "I believe you'll pull the trigger. I just don't believe - you'll hit anything." And then he goes into a dive. Sadly, this is just a few moments before Aeryn takes her chair-dive into the frozen lake.

Halo 3, "The Crow's Nest" level. The Chief and Johnson reach the Command Center and start making plans to attack Truth's army, but then Truth appears on all screens and says: "You are, all of you, vermin. Cowering in the dirt, thinking...what, I wonder? That you might escape the coming fire? No! Your world will burn until its surface is but glass! And not even your Demon will live to creep, blackened, from its hole to mar the reflection of our passage; the culmination of our Journey. For your destruction is the will of the gods! And I? I AM their instrument!" Okay, so that's not a space battle. But I love that speech.

Galaxy Quest. Jason and Sarris have many great confrontations over the viewscreen, including the first one, where Jason thinks Sarris is just acting, and the second one, where Jason calls Sarris stupid and ugly because he thinks the sound is off. But the best, by far, is the final jaw-dropping confrontation. Sarris reminds Jason that he's a General, who's seen war and death that Jason can't imagine, and Sarris won't blink no matter what. (This scene is lengthier in the original script, actually.) But Jason retorts that it doesn't take a great actor to recognize a bad one, and Sarris is sweating. And then we get to the classic exchange, "You fool. What you fail to realize is that without your armor my ship will tear through yours like tissue paper." To which Jason responds: "Yeah. Well what you fail to realize is... I'm dragging mines."

Babylon 5, "Between The Darkness And The Light. We're totally embarrassed that we missed this crucial showdown between Earthforce and Susan Ivanova, and super grateful that commenters Michael and BcBeBop pointed it out to us. I am going to start calling myself "the right hand of vengeance" and "the boot up your ass" in the same breath now:

Doctor Who, "Bad Wolf." Another one we're embarrassed we missed originally. Thanks to commenter AspiringExpatriate for pointing it out! I love how Christopher Eccleston's Doctor is just like, "No." As if it's not even worth arguing. It mirrors his awesome "No" in "The Long Game" when The Editor asks that long-winded philosophical question about whether a slave is still a slave if he doesn't know he's a a slave. I have to admit, every time I watch this scene I wonder why the Daleks don't just say, "Okay then," and exterminate Rose right then and there.

So what classic space talk-downs did we miss? Feel free to let us know in the comments, but only in the most trash-talking, mouth-running, space-taunting way possible. You fools! We're laughing at your superior intellects.