A Sequel Hook is something in a work that suggests that there is a clear possibility for another story. The MacGuffins may come in threes, the Big Bad might be Not Quite Dead, or, more blatantly, as the story ends another adventure might be shown beginning.
The original work still has closure but, by leaving minor plot elements unresolved, the writer has made writing a sequel easier. If the audience demand is there, they'll be ready. In fact, this method is so common the audience will identify any unresolved plot element or any ending short of Happily Ever After or Kill 'em All as a hook. Sometimes the hook was just that, the writers are not sure which direction they would be going in the later movie.
Pretty much every film based on a comic book sets itself up for a sequel, and any movie that goes out of its way to establish a very expansive universe that has room for a sequel. In the case of adaptations their source is usually a medium known for making multiple storylines and, in most cases, have a decades-long Myth Arc to mine for ideas.
If the Sequel Hook revolves about a character other than the main character, it may indicate a possibility of Changing of the Guard.
Make note that a Sequel Hook is not a combination of a Mythology Gag you noticed and wishful thinking. This is where the movie takes a brief side glance to let you know that more is coming. This is recognizable to almost anyone watching/reading, not just the fans that notice a minor gag in an adaptation.
If the story is complex enough, there can be a fine line between this and an outright Cliff Hanger. And the two can overlap if the story concludes, everyone's happy and then a new problem shows up to put everyone in turmoil.
If a movie poses a Sequel Hook only for no sequel to ultimately be forthcoming, this can be the source of unintentional humour later on down the track.
Compare The End... Or Is It?, Here We Go Again, The Stinger, And the Adventure Continues, To Be Continued, Saved for the Sequel. Can occur as part of Inescapable Horror.
It had been made clear in Tokyo Mew Mew that Ichigo and friends had been de-powered because there was no need for them to fight. Then, we see everyone back at the cafe months later and, depending which version you're following, either their marks have reappeared and they transform, or Ichigo's catears reappear and Berii looks in the cafe window.
A post-credits sequence in Strike Witches features Yoshika receiving a letter from her supposedly-dead father. But seriously, who saw the first two episodes and thought he was actually dead in the first place?
The ending of Petite Princess Yucie has all the lead girls inexplicably attend the Princess Academy once more, even though they all graduated already. Yucie also seems to be no different as a Platinum Princess. But it's especially clear that a sequel was planned when all the girls shout "see you again" in the last shot. This was in 2003 and there still is no sequel in sight.
Subverted in Fatal Fury: The Motion Picture, when Geese shows up halfway through the film to show us his RAGING STORM... and then is absent for the rest of the movie. Sequel time? Nope, they never made another.
Bamboo Blade has Tamaki and a long-haired girl turn their heads to each other in the ending credits. Les Yay aside, this could mean that there is more in store.
Giant Robo has possibly one of the most sadistic, but not because of any fault of the writers'. The final OVA episode ends with the Earth decimated but able to recover, the IPO gutted of several of its top men, and Smug Snake Koumei informing the Magnificent Ten that all is according to the plan of Lord Big Fire, with Operation BR about to begin, suggesting that Big Fire is about to launch a true operation to conquer the world after Genya's plot both crippled their major opponent and simultaneously made sure the world would survive to be ruled over, leaving it ambiguous as to whether the entire operation was masterminded by Koumei or Big Fire himself. However, the sequel was unable to be made due to funding problems, so several critical explanations and Koumei's presumed come-uppance were never actually made, much to the frustration of the OVA series' many fans.
Witchblade is practically BEGGING for a sequel. Due to its cliffhanger ending, canon incontinuities, and the fact the title artifacts parents (Angelus and Darkness) never got a role pretty much leave this show somewhat unresolved. If the comic writers give a shit about their canon (and the anime IS PART OF IT), they should bloody well rectify this.
The last Slayers light novel ends with Lina and Gourry traveling to Lina's homeland, Zephilia. Cue loads of Will They or Won't They?. There's also the fate of Zelgadis and Amelia, considering that they were left to their own accord after the eighth novel (their replacements were Killed Off for Real in the last two novels), and Zelgadis' side story takes place after that time.
The second anime season ends with Sylphiel running off with the heroes, but she's nowhere to be seen in the third (being replaced by Filia), so this is a subversion. Also, the last season has more of this than the third did, with Zelgadis riding on a boat contentedly sticking out among them.
The second season of Hayate the Combat Butler ends with a new semester beginning for the cast, as well as a very brief shot of Athena during the final credits.
For Heroman, Kogorr is defeated, and everyone is happy as the episode ends, fading to black. But, then it fades back in to show a prison island, with lights blazing and alarms shrieking. The prison's guards get decimated by Veronica, who frees Those Two Guys, and breaks down the wall to a certain cell, filled to the brim with equations and formulas, as well as drawings. A pencil is spit to the floor as the cell's inmate turns around: Dr. Minami. Cue To Be Continued. We even see a question mark afterwards.
Pokémon Special would always use this at the end of an arc. It may seem a little silly, as the release of a new Pokémon generation already indicates a coming sequel, but it is often done to show either the new Big Bad, the direction they'll be heading with the next chapters, or just a way to explain how one arc leads to the next, chronologically.
Red/Blue/Green - Averted. It makes sense for the first chapter, though, as there's no way they would've known that a new Generation of Pokémon would even exist (Yellow was out at the end of this arc, not Gold and Silver.) or if they would even continue with the series.
Yellow - As part of the story, it's revealed that Yellow's journey had been engineered by Blue (The girl). While her reasons are not revealed, she's shown on her PokéGear calling someone, discussing that she hadn't found what she needed through Yellow's adventure. The next we see is Silver, the rival of Pokémon Gold and Silver, hanging up, and a shot of Johto with a group of Generation II Pokémon as the chapter ends.
Ruby and Sapphire - HUGE. After the battle, the Red Orb and Blue Orb used to maintain Groudon and Kyogre shatter into pieces. A shadowy figure shows up and picks up the pieces. Holding two red and blue shards, he says, reciting what comes across as a prophecy, "Creation of the new world order lies in thy hands." Next we see Giovanni, standing there with the shards, where his last words at the end of the chapter are "...And it has already begun."
Especially shocking as this occurs after a Happily Ever After ending, where almost every loose end is tied up.
FireRed and LeafGreen - Arguably larger than Ruby and Sapphire's. After the Big Bad is defeated and the characters all get their just endings, Sird shows up as Mewtwo flies away, using the last amount of energy she could attain for one last attack... Which turns the Pokédex holders to stone. And with that, the arc ends.
Emerald - Crystal, looking back at the photographs from the battle, recalls Archie's last words when she confronted him about the origins of his suit of armor. She asks him who gave it to him, but he can only get out the beginning of the word before dying, as his last word is: "Galac..."
Diamond and Pearl - So Cyrus has been defeated, Dialga and Palkia are peaceful again, and Platinum has finally achieved her goal of making the Berlitz family crest. Everything should be back to normal now, right? WRONG. She then states her intentions of rescuing her original bodyguards, then a weird scientist suddenly shows up, Byron and the researchers stop him, but they accidentally manage to open up a black hole, where a large claw swoops down and sucks in Dialga, Palkia, and Cyrus. The scientist just grins, tells Platinum his name and about the Distortion World, and escapes. Dia manages to take his notebook from him, which reveals information about the legendaries. Flash forward to Flint and Volkner having a conversation, where Flint reveals that he's in the Battle Zone. Another flash forward two weeks later, where Platinum's mother is on a cruise ship, and she and her daughter have a talk about the Distortion World.
An episode of Pokémon that took place near the end of the Kanto arc ended with a shot of Mewtwo destroying the Team Rocket base and flying away, therefore setting the stage for Pokémon: The First Movie.
Panty & Stocking with Garterbelt ends with what is basically an Up to Eleven version of this trope, with sudden, completely nonsensical plot twists thrown out left and right just after everything has been resolved. Basically, Stocking pulling a Face-Heel Turn and slices Panty into 666 pieces, and Big Bad Corset pops out of Brief's penis (It Makes Sense in Context, I swear) to tell Brief that if he wants to save Panty, he must follow the pieces to the next town and unlock the hellgate there. Your typical Gainax Ending, as it were, but taken to eleven.
Also, the whole thing may actually just be a parody of this trope; the creators have been very coy about a second season, and it's quite possible they have no intention of making one and came up with an asspull sequel hook just to troll the fans.
It's also quite likely that, knowing them, they will make a second season but completely ignore the cliffhanger.
Gundam 00. Both seasons. Season one: Setsuna's line: "As long as the distortion continues to exist, I will continue to fight... Alongside my Gundam." Also, Tieria's "This is the Gundam that will change the world..." while we see a container saying "GN 00 00 GUNDAM". In season two, Tieria's "The true goal of the Aeolia Plan was to prepare Humanity for the dialogues to come." And after the Credits, we see a 15 second teaser for the movie, which ends with the text: "2314: The Childhood of Humankind Ends." If those don't practically say "There'll be another season" and "We're planning on making a movie", I don't know what does.
Fullmetal Alchemist averts this to the point where it seems like the writer was literally trying as hard as possible to prevent any possible sequel or need for a sequel. The 2003 anime version on the other hand ends with Ed getting ready to do another transmutation to get Al back by sacrificing himself. The Conquerers of Shamballa movie fittingly picks up a short time after the hook, with Ed stuck in the "real" world after his transmutation was successful.
The creators of Death Note have themselves admitted that they are undecided whether The Death Note that Aizawa was holding at the warehouse was real, or if Light's bluff about it being fake was true. They claim that if the book was a fake, the real one is still out there somewhere, meaning "Ryuk could return somehow..."
In Pretty Cure All Stars New Stage, when Ayumi returns to normal from being Cure Echo, the uniform's bow drops off, turning into a Cure Decor, the MacGuffin for Smile Pretty Cure!, but it is never picked up by either Ayumi nor the Smile team. Sadly, while Ayumi makes a cameo in New Stage 2, that's the extent of her appearance and thus we may not see her in action again.
In the 13 and a half episode (no, seriously) of Tenchi Muyo!, after Mihoshi and Washu have their talk and we see what Washu's doing to Ryoko, we're cut to a scene where D3 is talking to Tokimi and we see a mysterious figure in the shadows. That figure, Z, would show up in the third season.
As well, in episode six, we're introduced to Washu, who's Ryoko's "mother" and is incredibly smart, and Tsunami, who has a major connection to Juraians and Sasami in particular. Both of those are explored more in the first two episodes of the second season.
Tiger & Bunny had the Ouroborus symbol appearing on a Stern dollar at the epilogue of episode 25. Also, Kotetsu and Barnaby coming out of their retirement and joining the Second League Heroes.
In the final episode of High School Dx D, Sirzechs and Grayfia were discussing about how the Red Dragon Emperor (Issei) is now part of the devil society. It seems they were happy about Issei crashing the wedding until Grayfia mentions that the Vanishing Dragon will make his appearance. Cue the second season of the anime.
Double Subverted at the end of part 1 of JoJo's Bizarre Adventure. Dio is defeated, Jonathan and Erina are married, they're boarding a ship to America for their honeymoon, everything points in the direction that the story is now ending. Oh, some guys are carrying a treasure chest onto the ship with a still-alive Dio in it, how cute. Hang on, we're seeing what happens right now? Hold the phone, did Dio just kill Jonathan?! Well, darn, that's a bit of a Downer Ending... wait, Erina is pregnant with Jonathan's child? The Joestar legacy lives on! Rejoice!
A comic book example is found in the six issue Marvel Boy limited series from 2000. At the end, Marvel Boy ominously tells the government agents that in five months, the super prison he is in will become the capital for the new Kree Empire. After that, the caption advertises Marvel Boy 2:001!!!, a title that will likely not see the light of day, since Marvel Boy's next appearance was during the 2006 Summer Event Civil War.
At the end of Spider-Men, Peter makes it back to his own universe and starts wondering if his dimension has a Miles Morales (the new Ultimate Spidey). We don't see the results of his web search, but Peter is stunned.
The last chapter of Mortality sets the stage for the next novel, The Road to Reichenbach, by showing Sherlock Holmes receiving an offer from the French government (as mentioned in "The Final Problem"). The epilogue goes on to sum up the characters with the Reichenbach Falls used as a motif.
Post Nuptials, the first story of The Nuptialverse, deals with the emotional fallout of Twilight's friends not believing her in "A Canterlot Wedding", and while most of it is dealt with, Spike still feels incredibly guilty and won't speak to Twilight. Meanwhile, Rainbow Dash senses something is wrong with Scootaloo, and Pinkie is dealing with her own family issues. All of these problems are dealt with in the sequel Families.
The side story Metamorphosis ends with Chrysalis swearing revenge on Twilight, Shining Armor, and Cadance.
Families ends with Discord contacting Chrysalis in a dream and ordering her to meet with an "associate" of his in order to plan his release. Meanwhile, relations with the dragons are now tense due to Garble's actions, and on top of that, several canon Season 3 events are alluded to (Trixie plotting her revenge, the reemergence of the Crystal Empire).
At the end of Earth and Sky, Chrysalis is still on the loose, and has embarked on a scheme to replenish her strength by becoming a beloved foal actress.
In the Total Drama story, Courtney and the Violin of Despair, Courtney acquires the similarly cursed Violin of Doom at the end of the story. Subverted in that the story's closing note of uncertainty is actually a nod to the sci-fi classics of the 1950s, which tended to leave room for a sequel despite there being no plans for a sequel. So far as is known, the author has no plans to actually write a sequel (which would obviously be titled Courtney and the Violin of Doom); but he has stated that if he ever does, it might be something like The Perils of Pauline and would probably be openly pro-Courtney as opposed to the revenge fic subversion of the original.
Faith and Doubt ends with the words "End of Volume 1" and credits. It then cuts to the five remaining elements of harmony discussing their plans to invade Equestria and take over the bodies of the Bearers.
The sequel, The Abundance, does it again: Everything is wrapped up and the characters get a happy ending... except Princess Celestia and Luna's adopted father, Lord Tydal, escapes from the afterlife to warn them that the precursors to the ponies are coming and will be bringing hellfire with them.
The Justice League of Equestria series has a setup of each story having two sequel hooks — one for each individual story's potential sequel, and the other being part of the setup for the eventual main crossover between all the storylines:
Mare of Steel: First, there's the fact that Silversmith is still free, and has samples of Supermare's DNA to experiment on. Then, the last scene shows Darkseid opening a boomtube to Equestria.
The Princess of Themyscria: Ares, defeated by Diana and now trapped in Tartarus, meets Circe, setting up a future Villain Team-Up. And then the last scene has Athena revealing to Hippolyta that Ares opening a portal to Tartarus has created a crack in reality that Apokolips can take advantage of.
Shadows Awakening: The epilogue involves Captain Black recruiting the J-Team to head a new subdivision within Section 13 dedicated to magical threats, Tohru becomes a full chi wizard and takes on Jade as an apprentice, and in the last scene, Daolon Wong's apprentice emerging to take control of his resources, and the Big Bad mantle.
MLP Next Generation: Know Fear! ends with three hooks: Starburst dedicates herself to continuing to fight the war, even as a renegade; meanwhile, unknown to her, Nox is raised as a Black Lantern; and in the final scene two more power rings — one orange, the other violet — arrive on Equestria. And a sequel has already been announced, and confirmed to, at least, address that last hook.
Films — Animated
The Incredibles ends with the Underminer rising from below the city streets and the Parr family reacting by all masking up. Even Jack-Jack. Ultimately, The Incredibles: Rise of the Underminer was made into a video game. A sequel is also planned for later on this decade.
Parodied in The Simpsons Movie, where the family is watching the credits at the end. Maggie's first word is "Sequel."
Kung Fu Panda seems mostly free of these, despite there being one sequel in the works already (and supposedly four more), with the end credits mostly being just shots of village life and Po interacting with Shifu and the Five—even the last image of the new peach tree growing is more a call-back to Oogway and Po's future as a kung fu warrior. But with the movie and characters structured the way they are, sequel hooks almost aren't needed; the kung fu genre in general lends itself well to episodic campaigns—i.e., Po and the Five fight Big Bad or Monster of the Week to rescue this or that artifact. The only possible Sequel Hook (which is debatable) is if in the climactic battle, Tai Lung was actually killed/vaporized by the Wuxi Finger Hold, or just KO'd. Only time will tell whether this scene was meant to imply a sequel or not.
In hindsight, the blatant Unreveal of why Po has a goose for a father could be considered the real Sequel Hook for the first film, this question finally being answered in the second.
Kung Fu Panda 2, however, ended on a definite Sequel Hook with The Reveal that Po's biological father and several other pandas survived the genocide of their kind.
Invoked at the end of The Rescuers where the child in distress at the end of the film is actually implied to be from Australia.
Back to the Future: Doc Brown whisks Marty and girlfriend Jennifer away at the end of the first film. The writers merely intended it as a closing gag, and later had to work out why he whisked him (and her) away.
The ending of the first one was meant to just be a gag and there were no plans to actually do anything with it. (Word of God states that they would have not put Jennifer in the car if it was planned as a sequel hook, note that she never does anything but be unconscious.) The ending of 2 is both a sequel hook and a Cliff Hanger. 2 and 3 were filmed as essentially one movie with a division between the stories. Part 2 actually ends with "To Be Concluded..." and a preview of Part 3. Not too bad on a DVD where you just pop the next disk in but a bit annoying on theatrical release.
That repeat of the end scene of part 1 at the beginning of part 2, while looking like a continuation picking right up at the Sequel Hook, was actually a re-filming of it with a minor Retcon, so that the new actors could match up with the footage to follow, and so that they could subtly insert a moment in which Doc has a new reaction to Marty asking whether he'll become an asshole in the future that is more appropriate to what Part 2 portrays. (In the original version of the first film's end scene—the one from the first film—he immediately brushes off the question with a sincere-sounding reassurance that "both you and Jennifer turn out just fine". In the re-filmed version of the scene at the beginning of part 2, he says the same line, but this time hesitates first with some hems and haws and an "oh shit, I wish he hadn't asked me that" look in his eyes.) A rare case of a Sequel Hook actually going against itself.
Also, the "To Be Continued" at the end of the first film was not added until the video release, after the studio had already greenlit a sequel. The original theatrical cut did not contain it, so it omitted on the DVD release.
The second movie uses the 1955 'end' of the first as a hook; as soon as Marty's gone back to the future and Doc Brown's celebrated his good work, the Marty from slightly later in the future appears and tells Doc that he's "back FROM the future!"
Averted in Mean Girls. The sequel has no recurring characters aside from Principal Duvall. It might appear that the "Junior Plastics" seen at the end are this, but the sequel focuses on a completely different cast of characters.
Which makes it all the more awkward if you, like me, saw the sequel soon after on video and therefore found it all the more obvious just how utterly different the blatantly human, normal-sized Shao Khan it portrayed was compared to the CGI monstrosity with several arms filling the sky and speaking in a booming, demonic voice.
Superman is a rare case of a film having a sequel hook at the beginning; General Zod, Ursa, and Non are banished to the Phantom Zone in the film's opening scenes, and are not seen again until they return as the Big Bad and Dragons in Superman II.
That's because Superman 1 and 2 were originally filmed together. After the entire project fell behind schedule and over-budget, the studio called Richard Donner up and told him to finish up the first film and leave the sequel for later. Still a hook, but not necessarily a dangling one.
X-Men: The Last Stand, despite being the final chapter in a trilogy, has a potential sequel hook in its final seconds; the de-powered Magneto, homeless and alone, sits at a (steel) chessboard in Central Park vainly trying to make the pieces move; one pawn wobbles, almost imperceptibly, in the instant before the shot cuts to Brett Ratner's director credit. There is even a second hook after the credits, showing that Xavier survived in the Chekhov's Gun. (eww.)
The Stinger at the end of X-Men Origins: Wolverine shows Logan drinking away his sorrows in a Japanese pub. Logan's next solo film, The Wolverine feature Wolverine's adventures in Japan.
Due to the poor reception of Origins, The Wolverine actually ignores the events of Origins, and instead takes place years after the events of The Last Stand.
X-Men: First Class ends with Erik becoming Magneto for the first time and busting Emma Frost out of prison.
The Wolverine ends with Wolverine and Yukio heading out to have new adventures across the globe, with Logan finally having accepted his role as a warrior and hero.
Two of them in X-Men: Days of Future Past. First, Mystique rescues Wolverine from the river Magneto threw him in, though we know that turns out alright. The Stinger gives us a glimpse of Apocalypse and his Four Horsemen.
The Garbage Pail Kids Movie, of all things, had one with the titular kids escaping and hitting the road. Thankfully, it flopped at the box office and no sequel was made.
A very similar "single left-over egg hatching" sequel hook is the final shot of 1982's Q: The Winged Serpent. The film didn't do well enough to merit a sequel.
Species II completely ignored its predecessor's hook: a rat eating the corpse of one of the aliens, and getting possessed from doing so.
The 2007 TransformersLive-Action Adaptation had four hooks; Optimus's message to other Autobots at the end, Megatron's corpse dropped in the Laurentian Abyss, Starscream leaving the planet during the credits and Optimus picking up a fragment of the movie's MacGuffin.
At the end of the sequel, Megatron and Starscream grudgingly pull a Villain Exit Stage Left, at the latter's suggestion ("Sometimes, cowards do survive"). It also has this line about Optimus Prime and the Transformers in general:
Lennox: If God made us in His image, then who made [Optimus]?
Age of Extinction has two hooks; Galvatron planning his revenge and Optimus Prime flying into space to confront his creators.
The 1980 Flash Gordon movie had someone pick up Ming's ring after the story ended; since the movie was a bomb, nothing came of it. Possibly in homage, the third series of the revived Doctor Who ended with someone picking up the Master's ring and laughing evilly.
The original ending of National Treasure was thought to be a Sequel Hook by test audiences, so the filmmakers shot a new ending and put that one in the movie. (You can see the original ending on the DVD.) Ironically, the film made so much money that it got a sequel anyway.
Ironically, played straight in the sequel, Book of Secrets. At the end of the film, the President asks Gates to look into the mysterious Page 47 of the titular book. Though the contents of the page are never mentioned, Gates describes the information contained within as "life altering".
Biggles Adventures In Time finished with our American time-traveller getting zapped in to help Biggles escape from a cannibal cooking pot. It may even have finished "To Be Continued..." The film bombed and no sequel was made.
The 1998 film version of Lost in Space does this as well: all is well and the villain has been spared and is still aboard, but suddenly a Negative Space Wedgie threatens the ship. The only option is to hit the button that randomly zaps the ship to another point in the galaxy (why do they even have that button?) to who-knows-what adventures. We don't know what adventures: the film bombed and - you guessed it...
"Aaaand his Eyes Open." "His eyes open!" "Hurry up and show it!"
Blade: Trinity: The audience is led to believe that Blade died fighting Drake/Dracula, but just before the credits roll, Drake is still alive, and the audience sees Blade riding away on his motorcycle, set to fight again another day. This actually depends on which cut you're watching.
XXX State Of The Union ends with Gibbs entering an elevator while discussing with his anxious attendants who he has in mind for the next candidate for the xXx position.
Iron Man 1 has at least two, and possibly three hooks. James Rhodes looks at the older Mark II silver-and-grey armor and says "Next time, baby", an obvious foreshadowing of his becoming War Machine (ironically this is not to be, at least for Rhodes' actor). The name of the Asian terrorist group, "The Ten Rings", was mentioned, which indicates that the Mandarin will eventually be appearing. And the brief after-credits scene involving Samuel L. Jackson as Nick Fury declaring the existence of other superheroes and the "Avenger Initiative" is about as blatant as a Sequel Hook can get without being a Cliff Hanger.
The Incredible Hulk had at least three as well; Hulk not killing Abomination, Samuel Sterns turning into Leader, and Tony "Iron Man" Stark making a cameo announcing that they're putting a "team" together.
Except that minor handshake got retconned with the release of Captain America: The First Avenger when the scientist who was responsible for Steve's transformation was renamed "Dr Abraham Erskine".
Don't forget Bruce attempting a controlled transformation with an ambiguous smile on his face. According to the DVD commentary, whether the smile indicates that he'd actually gained control or not would depend on which came first: another Hulk movie (where Banner wouldn't be in control) or The Avengers (where he would).
While not exactly sequel hooks, the director has confirmed that the superhuman map scene with Fury was meant to foreshadow other Marvel characters who were being primed for future film appearances. The most notable might be the indicator in Africa, meant as a nod to the Black Panther.
The Avengers itself ends with the Other lamenting the Chitauri invasion has failed as humans are "too unruly", and claims trying to take them on again would be "courting Death." Cue The Reveal of Thanos, smiling at the thought.
Also...Tony making some modifications to the Stark Tower, to perhaps accommodate his fellow Avengers should they ever be needed to assemble once again.
And now we have Thor: The Dark World ending with Loki sitting on the throne of Asgard and impersonating the Allfather after faking his own death.
Not to mention The Stinger, which shows the first appearance of the Collector, from Guardians of the Galaxy, being given the Aether to look after by Sif and Volstagg. It also announces that the Aether and Tesseract are Infinity Gems (yep, THOSE Infinity Gems), and the Collector wants to acquire them all. "One down, five to go."
The Dark Knight itself has a huge sequel hook, edging into cliffhanger territory: The series can't very well end on Batman being demonized and hunted, so how will he atone for Two-Face's crimes and regain Gotham's trust? Yet that ending is so organic and un-gimmicky it takes a minute to recognize it as a hook.
Alien vs. Predator: The PredAlien chestburster at the end prompted an immediate reaction of "Well, they've set up the sequel nicely then..." and sure enough, said sequel opens on the same scene, even. Reshot, admittedly, but recognisably meant to be identical.
The sequel ends with a Sequel Hook of its own. At the very end, Colonel Stevens puts the predator's gun in a box saying that "This isn't for our world, is it Ms.Yutani?" and it ends just like that. Unfortunately, due to the poor success of the first two, they probably won't make a third one.
Each film of the prequel trilogy had a Sequel Hook as well: The other Sith still hidden from the Jedi at the end of The Phantom Menace, the start of the Clone Wars at the end of Attack of the Clones, and Obi-Wan, Yoda, and Bail Organa making their plans for the future at the end of Revenge of the Sith (the last one, of course, leading up to the original trilogy).
They weren't quite as stupid as that makes it sound. They took it away from him, but he took advantage of his guards being (literally) off-balance due to Alex firing on the command ship and got it back.
The dire and dismal Hawk the Slayer has this one on its list of crimes. Hawk's evil brother, Voltan, appears to Hawk and Co. to be acting alone, but the audience can see that he is just a subservient Dragon to the shadowy, hidden Big Bad. He gets killed, but the final scene sees his corpse being borne away from its burial chamber by said Big Bad for resurrection. Fortunately, it didn't happen.
Spoofed in Kung Pow! Enter the Fist (as most things were in that movie), both when Wo claims to meet the Chosen One again... "many times... in the sequel". There is also a clip of a "sequel" at the end of the movie, but this is comprised almost entirely of scenes that got left on the cutting room floor.
The trope image is from Mac and Me, which ended with the eponymous alien and his family becoming U.S. citizens and driving off in a car with a sign on the back with a big pink bubble showing up at the end saying "We'll be back!". Thankfully, this was not followed through with due to the movie's box office failure. Mind you, this is the same movie that shamelessly ripped off E.T. and featured product placements up the wazoo.
Young Sherlock Holmes features a post-credit reveal that one of the characters in the film would eventually become Holmes' nemesis, Professor Moriarty. Shame that there was no sequel (beyond the books, of course), because the flick wasn't that bad.
A title at the end of The Sword and the Sorcerer announces that its sequel would be called Tales of an Ancient Empire. It was never produced.
Until 2010, that is. Not that the sequel has much to do with the original...
Resident Evil: Retribution ends with Wesker injecting the T-Virus back into Alice, and Wesker tells Alice, Jill, Ada, and Leon that the Red Queen has declared an all-out war on humanity, and that this is the last stand.
In the same canon of the original games, Resident Evil: Degeneration shows that WilPharma's assets have been acquired by TriCell. The ending for the ride Biohazard 4D Executer has Dr. Cameron escaping the city, having become a practically immortal creature capable of Grand Theft Me.
G.I. Joe: The Rise of Cobra: Cobra Commander (actually using that moniker, to be exact) and the masked Destro appear only almost at the end, the US President whistling a certain tune and the Joes going off on another mission.
G.I. Joe: Retaliation: Cobra Commander is still at large and there's a possibility that Destro, who was left in the Prison by Cobra Commander, may return as a threat in a possible sequel.
The premise for the sequel is essentially set up in the last few minutes, because it's revealed that Moriarty stole the radio transmitter device and is willing to use his massive wealth to wreak havoc. Holmes agrees to go after Moriarty at the very end of the film.
Eragon ends with Eragon and his dragon defeating the forces of evil. Then shortly before the credits roll, the film's Big Bad slices open a large tapestry to reveal his own Dragon, which would presumably do battle with Eragon in the sequel. Luckily, Eldest (the next book in the series) was never filmed.
Slither ends with a post-credits scene of the alien Not Quite Dead and infecting a cat. Sadly, the film didn't do well enough at the box-office to get a sequel.
Plus Barbossa gaining Blackbeard's ship and magic sword and Jack regaining The Black Pearl, albeit stuck in a bottle, and heading off with Gibbs to find a way to restore it.
At the end of Ip Man 2, we are introduced to young Bruce Lee, who Ip tells to come back when he's older.
Anybody remember the Super Mario Bros.? Princess Daisy bursts into Mario and Luigi's apartment armed with a BFG, proclaiming "Guys... you're not going to believe this". Then everyone follows her out the door and the movie ends. There was no sequel, but nearly 20 years later, graphic novel sequels are planned.
At the end of the John Hughes movie Baby's Day Out, baby Bink picks out a book entitled "Baby's Trip to China", but due to the movie's gratuitous Tastes Like Diabetes moments, as well as Hughes' untimely death, the sequel never came.
Furious6: (Random man played by Jason Statham, right after ramming Han's RX-7: Dominic Torreto? You don't know me... But you're about to...
Maverick. When Maverick only hides half of his winnings in his boot, allowing Annabelle to steal the other half, he admits that he did it intentionally because it will be fun to get it back.
Dylan Dog: Dead of Night has a sequel hook where it is implied that Dylan and Marcus will have more adventures and fight new monsters (with a new monster appearing in the last shot). It is also revealed that Gabriel survived the vampires' attack against him. However, the film's poor reviews and box office will most likely prevent a sequel.
The Other Guys ends with the Big Bad still at large and rather ominously telling us that "soon, Lendl will be everywhere!" (Lendl is the corporation she runs). It's difficult to say if this was an intentional sequel hook, but it certainly makes for a good jumping-off point for a sequel.
This may have been more of a Here We Go Again moment than anything, since just prior to that, the members of the Mystery Team were all preparing to go their separate ways and off to college.
Merlin and the War of the Dragons ends with Merlin killing the evil wizard, Uther is proclaimed King of the Britons, general rejoicing and then Nimue resurrects the evil Wizard. The moie was made in 2008, I haven't heard of a sequel yet.
Fu Manchu Hammer horror movies always end with him saying "The World shall hear from me again."
Predators has the survivors watching a new bunch of people being brought into the deathworld to be hunted.
Waxwork ends with the wax museum of the title burning down and Mark and Sarah escaping, but the still animate hand of a wax zombie also escapes. Although it's not really the main conflict of the story, Waxwork II: Lost in Timepicks up immediately after that sequel hook, with the main characters trying to stop the hand from wreaking havoc.
Splice: At the end of the film, Elsa is pregnant with Dren's baby, and the boss thanks Elsa for her readiness to carry on with "phase two" of the project
Tintin: How's your thirst for adventure, Captain? Haddock: Unquenchable, Tintin!
Parodied in Men In Black II. After the big finale J notes that there's no way anyone didn't notice everything that just went down and no real way for the government to Hand Wave it away. The dialogue heavily implies that the events of the movie will cause the Men in Black to become public knowledge. Cue K using a large scale neuralyser hidden in the Statue of Liberty to erase the memories of the night of every single person in New York who isn't an MIB operative.
Innerspace ends with Jack Putter jumping into and spinning off in a convertible with the intention of stopping the now-miniature Victor Scrimshaw and Dr. Margaret Canker from harming the newly-married Tuck and Lydia.
Journey 2 The Mysterious Island ends with Anderson presenting Sean with Jules Verne's From the Earth to the Moon as a birthday present, saying it's an adventure he wants the whole family to take. The camera then pulls upwards, above the house, into the sky, into orbit and to just behind the moon.
Jack the Giant Slayer: Near the end of the film, set in modern day London, a boy named Rodey grins evilly at the royal crown (actually the crown of King Erik) and carries with him a backpack similar to Roderick's. This heavily implies that he is a descendant of Roderick (or at least a descendant of any siblings or cousins Roderick may have had, as he never had any children himself) and plans to do what his ancestor did centuries ago.
At the end of Master and Commander: The Far Side of the World, HMS Surprise finally catches up to the French ship Acheron after chasing it for 138 minutes. In the ensuing battle, the British win and capture their quarry. A prize crew is put on board to take it and the imprisoned French crew to a friendly port. As the captain of the Surprise relxes afterwards, his friend says something to make him think the French might attempt to recapture their ship, so the captain begins chasing it. Just as the audience thinks that the film might never end, it does, leaving the resolution of the chase for a sequel that, thus, far, has not yet been made..
The Musketeer (a 2001 adaptation of The Three Musketeers) ends with D'Artagnan whispering the Hook into the ear of Cardinal Richelieu: "Bless me Father, for I will sin. One night, I will come for you."
The Rocketeer ended with Jenny Blake giving Peevey back his reverse-engineered blueprints for a new and improved version of the rocketpack, which were stolen by Lothar earlier in the film.
A LexCorp logo adorns several trucks and building sites in Man of Steel, hinting at Clark's future Earth-born nemesis.
The end of Now You See Me desperately screams 'sequel'. Apparently it's getting one.
Parodied in History of the World Part I, which contains sequel hook material promoting History of the World Part II, which was never intended to be produced. Viewers were given previews of concepts such as 'Hitler on Ice' and 'Jews in Space', simply as an excuse to shoehorn such silly material into the film.
The Last Airbender: As with the show it's based on, it ends with a shot of Ozai assigning Azula the task of capturing the Avatar. But of course thanks to the dismal box-office returns, the planned sequels that cover the rest of the series were quickly scrapped.
Deliberately averted in Godzilla (2014) by Edwards. He says that he typically rolls his eyes at films that go out of their way to introduce plot points near the end for the express purpose of having them resolved in future instalments. He prefers to have a film that can stand perfectly well on its own.
Edwards:"I want a story that begins and ends, and you leave on a high. That’s all we cared about when we were making this; just this film. If this film is good, the others can come, but let’s just pay attention to this and not get side-tracked by other things."
In Running Scared (the 1986 comedy with Billy Crystal and Gregory Hines), two cop partners plan to retire from the force and open a bar in Key West after their current case. They crack the case, then decide not to retire. A sequel titled "Still Running" was planned and different scripts were written, but Crystal and Hines rejected them all as too weak.
Jurassic Park ended with one of these where Dr. Grant, being kept in Costa Rica by their government who was still investigating the Isla Nublar incident, is approached by an agent of the U.S. government about a path of destruction being carved through South America by a group of 'strange reptiles' that are swarming farms and devouring plants with lysine, the amino acid Hammond had all the dinosaurs bred to be dependent upon. Unfortunately this hook was ignored and the followup book was a sequel to the movie.
Rendezvous with Rama: After a mysterious alien object passes through the solar system, the book ends with the portentous sentence, 'The Ramans do everything in threes'. (Whether or not a second Rama, let alone a third, is presented in the sequels at all is debatable.)
After the Philosopher's/Sorcerer's Stone is destroyed at the end of the first Harry Potter book, Dumbledore says that there are still other ways Voldemort can return. Voldemort spends the rest of the series proving Dumbledore right.
Harry Potter and the Half-Blood Prince ends with Harry deciding to leave Hogwarts to find and destroy the Horcruxes that will make Voldemort vulnerable, which tells the reader that the series' traditional formula will be thrown by the wayside for the final installment.
Some fans really hope that the controversial epilogue is one of these, despite the author saying that it is not.
It's practically an anti- sequel hook, since it seems to only exist to assure us that they all lived Happily Ever After.
Believe it or not, J. R. R. Tolkien adjusted The Hobbit in a later edition to help it be the prequel of The Lord of the Rings. Which would make it a Retcon Sequel Hook. In the first edition, the Gollum was honest in the riddle game and showed Bilbo the way out of the caves in recompense when he realized he could not give him the ring.
Each book in J.R. Ward's crack-like Black Dagger Brotherhood series features a Sequel Hook embedded as the B- or C-plot of the current book. You'll be fiending for the next book before you've even finished the one you're on.
Terry Pratchett's Moist von Lipwig Discworld novels (all two of them) have thus far contained sequel hooks. In the first, Going Postal, the Patrician Lord Vetinari is seen making an offer to one Reacher Gilt to reform the Royal Mint as the Post Office had been in the book. This task was eventually undertaken by Lipwig in Making Money, and at the end of that one Vetinari muses how useful an asset Lipwig has proved to be and also how the City's tax system is in dire need of reform.
One of the next Discworld books is indeed rumored to be called Raising Taxes.
The epilogue-like last chapter of Ender’s Game is titled "Speaker for the Dead," and was written to set up the identically-named sequel to the book.
The last chapter of the first book of The Hitchhiker's Guide to the Galaxy is essentially an advertisement for the Restaurant at the End of the Universe. The place was encountered in the radio series immediately after the episodes adapted into the first book; the second book was indeed named The Restaurant at the End of the Universe but did not reach the Restaurant until the middle.
It's been claimed that the last chapter was added on by the editors to wrap up the completed pages after Adams missed his deadline.
The Death Note novel Another Note: The Los Angeles BB Murder Cases has a note by the narrator in the final chapter saying that, if he had more time, he would write about two other stories L told him. A pretty blatant set-up for more novels like it.
Dale Brown has various hooks in his book-endings. For example, Battle Born ended with the Dreamland staffers offering Rebecca Furness command of a new unit, while Air Battle Force ended on the then Russian president threatening another war with the Americans.
Older Than Feudalism: In The Odyssey, the prophet Tiresias tells Odysseus that he must make another journey after returning home, but this was not followed up on by Homer. That journey only appears in the lost Telegony, the last epic of the Trojan Cycle.
The hook involved with the Kang's Regiment books is rather unusual in that it's not only in the second of the existing books (that number itself implies a third volume, because Dragonlance multi-part novels almost always come in groups of 3) but in the ending of the War Of Souls trilogy. In Draconian Measures, the city Kang is trying to reach so he can found a Draconian civilization is named Teyr. The readers know from material set chronologically later that Teyr is a Draconian city, and there's an interesting bit in Dragons of the Vanished Moon where a bunch of Draconians from Teyr show up and fight againstTakhisis and her forces (keep in mind, Kang starts out as a faithful servant of Takhisis, so this is a Heel-Face Turn for him). Two unnamed but familiar Draconians appear among the collection of enemies Takhisis magics to her to watch the moment of her triumph, as well.
On the last page of Foundation and Earth, Isaac Asimov sets up a sequel (in a way that is somewhat difficult to summarize briefly or without massive spoilers). Unfortunately, he didn't actually have any definite ideas for that sequel and he died before he could come up with one.
Changes had Harry getting shot and dying as the last scene in the book.
Ghost Story has Harry set to head to the Sidhe Court as the Winter Knight to do as Mab bids, leaving his friends not knowing that he did not die.
Percy Jackson and the Olympians has a not so prominent one at the end of the last book, when the new resident Oracle spouts another prophecy. Though it is almost immediately Hand Waved with a "who knows when it could happen or if it's even about you guys" speech, it's pretty obvious that it will lead to a sequel series, which it has.
The last sentence of Year Zero pretty much spells this out.
Daemon ends with Sebeck and companion setting off on a road trip across America, leading into their part of Freedom.
Parellity ends with the main plot hook resolved, but some hanging threads, including Atlantis, what plans Abend has for Harborage and the gang, and everything to do with the Vaccine. Not to mention whatever the fuck was going on in chapter one.
The end of the comic neo-noir City of Devils has Nick's next case coming through the door: the witch Hexene Candlemas, hiring him to find her toad.
At the end of The Ultra Violets book 2, Power to the Purple, it's revealed that Opal and her mother have samples of the Iris's, Scarlet's, and Cheri's hair at BeauTek. Given the company's reputation for reckless genetic engineering, this is very worrying, to say the least.
In the Rainbow Magic series, the Weather Fairies series ended with the girls receiving the fairy lockets, which promised many adventures ahead.
Murderess ends with the introduction of a character named Tyler Killer, who is apparently very evil and probably not too bright, but extremely dangerous nonetheless.
A television show can do this with its story arcs; alerting you that just because the episode ends, the plotline will continue. Take the Star Trek: The Next Generation episode "Q Who". The Enterprise has narrowly escaped The Borg by the skin of their teeth. As Captain Picard and Guinan discuss their near-defeat, Guinan points out that humanity was never supposed to encounter them (the Borg) that early. But since they have....
Guinan: Of course, now...they know of your existence.
After Hiro Nakamura defeats Adam Monroe, he's shown trapped in a coffin, still alive; a clear indication that the character would return to menace the Heroes at some point later.
Also, Sylar's body disappearing at the end of Season 1. Heroes loved this trope.
Stargate SG-1 specifically left the door open on the Ori threat in its final episode, for the express purpose of setting up the follow up movie The Ark of Truth.
Word of God is that they were, for the first time ever, not expecting to be cancelled, so they didn't wrap up the current plotlines. Oops.
Doctor Who loves doing this in the new series with its season enders. Doomsday set up for The Runaway Bride. Last of the Timelords set up for Voyage of the Damned (and indirectly, for Time Crash). The End of Time set up for The Eleventh Hour (though in a sense any regeneration episode except Time and the Rani is a de facto Sequel Hook), and Steven Moffat has already said that The Big Bang sets up for the entirety of the next season (though the final lines, with the Egyptian Goddess on the Orient Express IN SPACE! is apparently a Noodle Incident). Oh, and Silence in the Library/Forest of the Dead? Set up for the run of River Song episodes this season.
After the Master's dead body is consigned to the flames in an attempt to prevent him from ever regenerating, Doctor and Martha go. Then we see a woman's hand pull the Master's ring out of the ashes.
The finale of series 6, The Wedding of River Song blows them all away with the reveal of the First Question. The Oldest Question in the Universe. The Question That Must Never Be Answered. That question is: Doctor Who?]]
The oldest Doctor Who stories ended like this. The first story "An Unearthly Child" has the TARDIS land on another planet and the radiation meter rise without the TARDIS crew seeing.
At the end of the Red Dwarf episode Polymorph, after the crew defeats the eponymous creature, it is revealed that a second one has made it on board. Subverted in the remastered version, in which on-screen text reveals that this one, much less intelligent than the first, took up residence harmlessly in Lister's underwear drawer and eventually died of old age. Doubly subverted by the episode Emohawk: Polymorph II three series later in which they meet another one.
Arrested Development ends with Maeby meeting with director Ron Howard and pitching the story of her family as a TV show. In an obvious bit of foreshadowing, the final line of dialogue has Howard saying the story might work better as a movie. Sure enough, the series has been Un-Cancelled for at least one season by Netflix.
The new season itself ends with a number of hooks for more episodes, such as George Michael apparently having impregnated a woman in Spain, Buster being accused of murdering Lucille 2, the web vigilante group Anonymous coming after the family, and Lindsay getting into politics.
Merlin: Arthur's gone, but there *is* that legend of how he'll return when Britain needs him most. Plus, Merlin's still alive in the present day...
This was also included in the season 2 finale, and in the season 3 finale as well.
Agents of S.H.I.E.L.D.: Season 1 ends with quite a few dangling threads for Season 2 to pick up on: Coulson is now Director of S.H.I.E.L.D. and tasked with rebuilding the organization after the HYDRA infiltration; meanwhile, he has started to compulsively draw the same alien symbols that Garrett did after taking the GH325 serum. Fitz, meanwhile, is left in critical condition after his near-Heroic Sacrifice, with his future uncertain. At the same time, both Quinn and Raina escape Garrett's downfall, the former still in possession of the gravitonium, and the latter getting in touch with a mysterious figure who is apparently Skye's father.
The season finale also had a nice subversion, where Garret starts to augment himself with cybernetic implants after everyone assumed he was dead. Right as it seems like he's going to be an even bigger threat for the second season, Coulson pops out of nowhere and casually vaporizes him mid-villain speech.
Henry IV, Part 1 ends with news that Northumberland and Archbishop Scroop are arming for war.
You'd think the "Part 1" in the title would kind of give away that a sequel was intended as well...
Henry VI Part 3 ends with Richard of Gloucester's (the future King Richard III) monologue where he talks about how he'll do anything to gain control of the crown- setting up for "Richard III".
Twelfth Night end with Malvolio pledging "I’ll be reveng’d on the whole pack of you!" which looks like a good setup for a tragedy to follow this comedy. Sadly, Shakespeare never did anything with it.
It has been argued that the sequel this set up was the real-life closing of the English theaters by the Malvolio-like Puritans.
Alien vs. Predator: In the latest game, you get three hooks for the price of one! first, you see Number 6 (the Alien) take over a Weyland Yutani ship and become a queen (future setting?), but you also see evidence that both the player character's Predator AND Karl Bishop Weyland are gunning for the Alien Homeworld as their next destination.
This franchise alternates between cliffhangers and sequel hooks:
Assassin's Creed I ends the past story with Altaďr finding the artifact that the modern Templars are looking for, and leaves Desmond hanging under stay of execution, pondering the twin revelations that he has developed Altaďr's Eagle Vision and that the entire laboratory that he's confined in is a Room Fullof Crazy marked up by the previous test subject in blood.
Assassin's Creed III ends Desmond's story and concludes the major story arc of the Meta Plot, but introduces the beginning of an entirely new Meta Plot: finding a way to prevent a vengeful Physical God that is released in the course of saving the world from enslaving mankind and recreating the First Civilization.
Axelay: After (finally) beating the Harder Than Hard mode, you get a message saying "see you again at Axelay 2". Too bad it never came out at all.
Episode 18 ends with Asura and Yasha putting an end to Gohma Vlitra, finally saving Gaea and beginning their trip back to Mithra. However, if you fulfill a certain criteria (ie gather enough S Ranks from the other stories) then you have the ability to play True Episode 18.
True Episode 18 has Asura and Yasha do everything as stated above, but when they do get back, Olga finally returns, attempting to kill Mithra as revenge for Deus. She is then promptly killed by none other than the Golden Spider, who reveals that he has other plans in store for Mithra. While this ending did look like it set up a plot for a sequel, it was eventually revealed to be more of a DLC hook when the final Part was released as DLC along with the Lost Episodes and two mid-episodes.
The True Ending DLC ends on more of a cliffhanger than the last one. After Asura kills Chakravartin at the cost of his own life and saves Mithra and Gaea for good, the post-episode interlude brings about another setting where everyone was reincarnated as apparently normal folk. At least, that is possibly the idea, if it were not for Not!Asura trying to face a meteor coming straight at him, mirroring the Japanese Cover Art.
Baby Boomer: If you manage to beat this incredibly difficult light gun game, you get an ending where Boomer makes it into the wrong baby carriage, and you are told to buy the sequel to see what happens next. Since this game was an unlicensed video game, it didn't sell well enough for a sequel.
The first game ends with one of these, showing that there aren't just one or two Children of Bhaal but HUNDREDS...
The second one does it by having an Omniscient Council of Vagueness monitor your progress. They turn out to be the Children of Bhaal the hero has to face off against in the expansion pack.
The Black Pits 2 adventure that came with the Enhanced Edition of the second game ends with the ostensibly master of the arena you'd been kidnapped to being killed by an unidentified 'master' for failing him, and your own group of adventurers teleported away to some unknown location by the Big Bad of the first Black Pits, who turns out to have survived/been resurrected.
Contained a Sequel Hook in an extremely well-hidden Easter Egg: hidden in Warden Sharp's office is another office, detailing what he plans to do if he wins the mayoral race - turning Gotham into a gigantic asylum, which lines up perfectly with the Spirit of Arkham message.
Batman: Arkham City, which did indeed result from said Hook has the following: The introduction of Hush and Harley being pregnant with the recently-deceased Joker's child.
Also: Azrael's prophecy of Batman's destiny for Gotham.
However, the Harley Quinn's Revenge DLC, it seems to reveal that the pregnancy test that Harley used gave a false positive, negating that particular sequel hook for some unknown reason.
In addition there is a boat in the game where if you use the cryptographic sequencer, you can open a hatch. Go down, and you'll find a dead body that jerks back to life if you examine it closely before dying, and a shipment order filled out to one "Johnathan Crane". If you also use the sequencer and move around the screen, you'll find coded messages from the Scarecrow saying he'll have his revenge.
Beyond Good & Evil: After the closing credits, shows a short cut-scene of one of the Dom'Z erupting from Pey'j's hand.
The Big Red Adventure: The Italian graphic adventure game, itself a sequel of sorts to Nippon Safes Inc., ended with the three protagonists on a camel in the middle of the desert, with a "The End" written in faux-Arabic font instead of the faux-Cyrillic used throughout the game. No sequel was ever made however.
BioForge: Dr. Escher survived and has been captured, with Dr. Mastaba gloating that she will be his next test subject. But alas, all hope for a sequel/expansion was long since gone.
BioShock 2: There's a audio log entry that has a scientist expressing the need to add some mental conditioning to their Big Daddies, because they aren't properly defending the Little Sisters like they were supposed to. The reason for this? At least one of these unconditioned Big Daddies just wandered off. A type of Big Daddy with weaponry, plasmids, and no emotional connection to a Little Sister. I wonder what use that could be for?
Blackthorne: In the ending of this game, after the credits have finished, there is a cutscene showing the same place on Earth where Blackthorne got teleported to Tuul from in the opening cutscene, and an orc teleports in, and laughs. The game was released in 1994, and there is no sequel yet, so there will probably never be a sequel. Meanwhile, the company that made Blackthorne got busy making a little game called Warcraft....
BlazBlue: Calamity Trigger: The true ending of this game's story mode is basically a non-ending that introduces the series' Big Bad, whereas The Stinger flat out states the storyline of one of the two new characters in Continuum Shift (namely, Tsubaki's).
The PlayStation port had new animated sequences that featured Lucca finding a baby out of nowhere, and the lost of the Masamune, all to link the game to its then upcoming sequel Chrono Cross.
The DS port gives us Dream Devourer which is presumably the Time Devourer from Chrono Cross. It also has Magus losing his memories which is a reference to a plot line in Chrono Cross that was abandoned during the making of the game. Which seems to imply that they may make a port for Chrono Cross for the PSP that redoes Guile's plotline to reveal him as Magus.
Conkers Bad Fur Day: The original ending involved Conker committing suicide, but it was changed to leave the possibility of a sequel. Thanks to Microsoft, there'll never be one.
Contra: The arcade version of Super Contra ends with an alien offspring flying off the final boss' head. The Famicom version of Contra also had a sequel hook that was removed from the American version.
Deadly Towers: The ending text hints that a new adventure might begin "about 1000 years" later, with "the coming of the Iron Age, and the revival of the Devil of Darkness." Of course, the game had no sequel.
Ends with a sequel hook in the form of Silhouette informing Crypto that there are branches of Majestic all over the world... however, the sequel subverts this, as it takes the plot off in an entirely different direction, and the possible sequel plot left open by the hook is resolved in the space of a single mission.
Destroy All Humans! 3 Path of the Furon ends with a large sequel hook. Before beginning the final boss fight, Crypto enthusiastically states "Destroy All Bosses and set up for the next sequel!" Also, after defeating the boss, Pox states "There will always be a reason to Destroy All Humans!" And after Pox takes the throne and Crypto prepares to leave for Earth, Crypto tells Pox "See ya in ten years! You'll like the future, I got a feelin' big hair's gonna be in style again!"
Unfortunately, with Pandemic losing the rights to the series, not to mention a few studios shut down during production, leading to Americans only getting the 360 version, as well as the PS3 version only available from Europe...
Diablo II: The original (pre-expansion) plot ended with one of these. The whole story has been set in flashbacks told by a crazy man in a madhouse named Marius who tells the Archangel Tyrael about how he travelled the world with Diablo himself and saw the three Prime Evils rise to power. Eventually he gives up the soulstone of Baal, Diablo's younger brother, to his visitor so all of it can finally end... TWIST! It wasn't Tyrael at all, but Baal in disguise. He kills Marius and takes his soulstone back and leaves to pursue unknown plans.
Diddy Kong Racing: The ending cutscene shows Wizpig, after his defeat, flying off the island in his ship laughing. The ending credits also featured a "To Be Continued" at the end. Rare was indeed working on a sequel named Donkey Kong Racing, but it became vaporware after they were bought out by Microsoft. Diddy Kong Racing's Nintendo DS remake didn't feature a "To be continued".
Donkey Kong Country: The GBA port has a different ending to the SNES original. K. Rool returns on the Gangplank Galleon just before the credits sequence and threatens to blow up DK Island. The Kongs jump off the ship into the water as it sails away, and Cranky effectively lampshades this trope:
Cranky: Call that an ending? Looks like a cheap stunt setting up the story for the sequel!
Doom: The ending of the original game has our hero escaping Hell and returning to earth only to find that the demons he's been fighting have already invaded, setting up Doom II: Hell On Earth.
Following the ending credits, Ness receives a taunting message from Porky, who is somewhere in time and space. This is followed with a "The End?" on the screen. The Japanese version however had a more unsubtle "To Be Continued..."
MOTHER 1 was sort of odd about this - the English prototype/Japanese Compilation Re-release had a definite sequel hook with Ninten being contacted by his father, saying something else had come up... except the actual sequel, EarthBound didn't have anything to do with Ninten, his family or anything else left unresolved in the game (Giygas aside, but his actions in MOTHER aren't so much as hinted at).
Ecco: The Tides of Time: "Instead of destroying the time machine, Ecco used it, and was lost in the tides of time." You were also given a "secret password" obviously meant for the sequel. Sadly, neither hook was ever followed up on.
Ends with hooks that could lead to a sequel, or even bringing the characters or setting into the rest of the Super Robot Wars series: A possible war between the Rubdor and Ezel, the exploration of the rest of the Mal Tierra (possibly leading to the discovery of full-sizedPersonal Troopers), and a hook in Original Generation Gaiden leading to Endless Frontier itself.
There is now a sequel, called Endless Frontier Exceed, and it adds two new lead characters and the story revolves around them, even with the return of the entire playable cast of the original title. Of course that means it'll probably explain the fates of Reiji, Xiaomu, and KOS-MOS considering they'll somehow still in the Endless Frontier.
Plays a twist of this one by showing a screen claiming you beat the game, with a promotional poster of "Eternal Darkness: Sanity's Redemption" at the end of a chapter (as part of the game's devotion to messing with the player directly).
A more direct example is the presence of a fifth, unknown Ancient which has been confirmed by Word of God.
Exit Fate: In addition to leaving several small parts of the plot unexplained, keeps the eventual fate of some main characters rather wide open and ends with a dark screen and text that can only be described as foreshadowing of some sort.
Ends with a fairly noteworthy one: Tidus, having performed a Heroic Sacrifice, finds himself in a giant, empty pool of water and swims for the surface with a grin on his face. The International version has an additional bonus movie that more directly sets up Final Fantasy X-2.
Final Fantasy X also has an in-universe inverted subversion. Tidus' father Jecht had a move called Sublimely Magnificent Jecht Shot Mark III. The reason for the Mark III? To draw crowds expecting to see Mark I or II, which don't exist.
Even bigger hook if you play the "Requiem of the Goddess" DLC story. The ending strongly hints that Lightning is going to return. And then a sequel starring Lightning was announced.
Fire Emblem Elibe (Fire Emblem: Blazing Sword): Provides an interesting Inverted Trope - the closing scenes of the epilogue, fifteen years later, introduce Roy and Lilina and demonstrate a now-adult King Zephiel's first encounter with Jahn. Of course, these are all things to do with the events of Sword of Seals, an already-released game to which Blazing Sword is a prequel.
Fire Emblem Tellius (Fire Emblem: Path of Radiance): Ended with some plot elements unresolved, namely the identity of the Black Knight, the behavior of the Rider Bertram, and identity of the person Sothe was looking for. This, combined with the enigmatic final words of Begnion's prime minister Sephiran, left fans hoping that the next game in the series would continue the story. The sequel, Radiant Dawn, does resolve the unresolved questions.
Unfortunately, Executive Meddling led to the third game being cancelled, so it's possible and likely that we will never know how Vader's freed by the Empire, just that he is since he kinda needs to be part of the original trilogy of films, which take place after the Force Unleashed games.
Gears of War: After blowing up the Locust tunnels with the Lightmass Bomb, it is revealed just before the credits that they are Not Quite Dead and will continue fighting until they win or die. Gears of War 2 continues the trend by leaving some unresolved issues and including a mysterious message after the credits.
At the end of this game, Kratos goes back in time to the War of the Titans, gathers them all up and brings them forward in time so they can collectively get revenge on the Gods for royally screwing them over. Kratos, holding onto Gaia, screaming up to the Gods, all while holding the Blade of Olympus: "Zeus! Your son has returned! I bring the destruction of Olympus!" The camera pans back to unveil countless Titans climbing up Mount Olympus, ready and raring to get a piece of the Gods. Talk about a... cliffhanger. Hah.
God of War 3 starts at that exact moment. Zeus repeats his speech to the other gods, albeit with a few slight changes. Kratos also repeats his final line before all the action starts.
The finale to the God of War trilogy also applies: Kratos fights his inner demons and forgives himself for slaying his family, using the power of Hope to defeat Zeus. Instead of giving said power to Athena, he kills himself, releasing it to the world. After presumably dying right before the credits, an additional scene is shown after the credits. A trail of blood leads from the scene of Kratos' death to the edge of the cliff he plunges off of at the beginning of God of War. But of course, none of this matters because it's confirmed by the creators that God of War 3 is the end of Kratos' saga. At least, if you don't take the whole "Platinum Trophy Secret Website" thing into consideration.
Not quite true. That "secret website" was just for promoting Ghost of Sparta so that wasn't a Sequel Hook but rather a Prequel Hook...or maybe more like a Spin-off Hook.
Golden Sun: Dark Dawn: Ends with Matthew, Karis, and Tyrell coming back home, only to find that the Mourning Moon has returned and ravaged their home, with their parents nowhere in sight.
Grabbed by the Ghoulies: Ended with Cooper and Amber walking towards the town of "Ghoulsville in the Gloom," and right before the final fade-out the silhouette of Baron Von Ghoul in his tiny biplane lurched across the sky after them, indicating he survived being thrown out of his window and may want a rematch.
Guild Wars: Eye of the North: The victory cutscene at the end of the main story ends with a brief glimpse of a gigantic dragon-like creature awakening in the chamber where the player characters have just defeated the Great Destroyer. Sure enough, Arena Net have confirmed that Guild Wars 2 will be set in a world dominated by ancient, reawakened dragons.
Halo 3 showed the presumed-dead Master Chief and Cortana drifting through space toward an inhabited planet.
Halo Wars even has an achievement called "Ready for the Sequel." Also ironic, due to Company Existence Failure.
Halo 4 doesn't have a hook for its main campaign, but the Spartan Ops campaign (which occurs six months after Master Chief's story) ends with Jul 'Mdama's fleet evacuating Requiem and Dr. Halsey defecting to the Covenant.
At least from 2 and up, always had the best ending possible show a limping man lamenting either humanity or how the Big Bad for that game could not finish off the protagonists, and how this same man still had plans despite such failures.
Many of these games features these, even going so far as to integrate them into gameplay so that the player has to finish certain tasks to get them.
Particularly annoying in the second game. The game always ends with a letter from King Mickey being opened and read, but not showing the player the contents and the bonus movie you can unlock as before shows a ludicrously vague explanation of the plot for the prequel. Yes, a prequel hook.
Kingdom Hearts: Birth by Sleep turns out to have a Distant Finale that is probably the biggest sequel hook we've seen yet, and that Distant Finale is a continuation of the second game's sequel hook, which pretty much refers to the other 3 games made after Kingdom Hearts II (coded, 358/2 Days, and Birth by Sleep. Combine their hooks and you get a massive sequel hook for Sora's new journey in a possible 3rd game to Reconnect Kingdom Hearts.
Re:coded gets a big one as well, revealing that Xehanort is due to return now that Sora has taken out both Xehanort's Heartless and Xemnas, his Nobody. Furthermore, Yen Sid is going to hold a Master Qualification Exam for both Sora and Riku in order to prepare them for the upcoming battle.
3D ends with Sora recovering from having his heart shattered and bathed in darkness, and the Big Bad not only alive and well, but almost finished assembling an entire new Organization. The secret movie you have to jump through the most hoops to get shows Yen Sid summoning Kairi to train with the Keyblade she got back in II.
King's Quest V: Absence Makes The Heart Go Yonder!: In the ending, Cassima is freed from Mordack and goes back to her homeland, Alexander mentions that he wants to visit her in the Land of the Green Isles, and Cassima mentions her Vizier who was the one who introduced her to Mordack. This sets up the plot of Kings Quest VI.
Limbo of the Lost: Of all the games in the world, this game ends with a sequel hook, showing Fate and Destiny about to pick another mortal pawn for their game and starting the whole process all over. Considering that the game was grounded for being bad and a major example of video game plagiarism....
Has one near the end of the first game, with Shepard saying there's still Reapers in Dark Space, and that they still need to be defeated. Shepard runs off, and... game ends. Though of course, it was revealed that it was planned as a trilogy before the game came out.
So, naturally, Mass Effect 2 with Shepard (or Joker, if Shepard died) studying the Collectors' data on Harbinger while the thousands of Reapers out in Dark Space prepare for their invasion.
The final DLC for Mass Effect 2, "Arrival," has Shepard blow up an entire solar system, but slow down the Reaper armada by several months. Hackett confronts the Commander on this and informs Shepard it won't be long before s/he's brought to Earth to stand trial for what s/he's done.
No matter what decisions you make in Mass Effect 3, the final shot is always the Normandy crash-landing in the middle of a jungle on an unidentified world. Every ending provides minimal closure or resolution to the status of the galaxy, leaving a gaping hole for future games or DLC content to use.
Also, if you have a ridiculous number of War Assets and pick the Destroy ending, then after the ending, you get a shot of a soldier in N7 gear lying in rubble, and then hear him/her take a breath. This has given rise to a massive number of fan theories.
The Extended Cut DLC helps to wrap the story up in a proper, less vague manner, and each ending gives more closure to the state of the galaxy, though there are still some potential sequel hooks here and there - Shepard still survives in the Destroy ending with enough war assets (a less-ridiculous number), and refusing to accept the Catalyst's options shows that the next cycle managed to defeat the Reapers, though the current cycle could not win conventionally.
In the Leviathan DLC, the eponymous Leviathan and his kin, the creators of the Catalyst and the FIRST advanced civilization, make it very clear that after the Reapers are taken care of, they will return to reclaim their spot as overlords of the galaxy.
Mega Man X had one after the end credits: Sigma shows up on a screen and taunts X, saying that his spirit still lives on, which turned out to be a hint about Sigma's true nature as The Virus.
Much later on in Mega Man X8, the Final Boss whacks Axl in the head, leaving an ominous-looking shard in the wound.
Mega Man ZX Advent: A secret ending shows Master Thomas preparing to continue what Master Albert originally set out to do. The former even recruited the enemy MegaMen to do his bidding.
Metal Arms: The last part of the credits shows Dr. Exavolt blasting off in a shuttle, cackling and saying, "I'm finished with you yet, Glitch!" Unfortunately after this game, Swinging Ape Studios was bought out by Blizzard to work on Starcraft: Ghost, and when that game became Vaporware, so too did Swinging Ape.
Metal Gear Solid 3: Snake Eater ends with an embittered Naked Snake becoming Big Boss, and with a call between Ocelot and his true employer the CIA Director, setting up the alliance between Ocelot and Big Boss that will give birth to the Patriots.
Metal Gear Solid: Portable Ops ends with another phone call, this time between Ocelot and "the Man with the same codename as Null" (Zero, hoping to invite Big Boss to form the Patriots.)
... until Metal Gear Rising: Revengeance, which ends with Raiden apparently striking out on his own to start a one-man war against the World Marshal PMC.
Ground Zeroes being a prologue ends with Snake managing to rescue Paz, Chico and the captives of Camp Omega and the mission a seeming success. Only for them to reach their base and find it under attack by a mysterious PMC, XOF. Snake manages to save Miller before the base is destroyed. Only for Paz to awaken and revealed there was another bomb in her body they missed. She jumps out the helicopter to save them. But doesn't clear the distance before she blows up causing the helicopter to crash and Snake and Miller seriously wounded and captured. And Chico's fate unknown. If that wasn't enough A post credit dialogue reveals that Skull Face wants to kill Zero, and interrogates Paz for his location, as Paz is one of the few agents that have met him personally. Paz agrees to give Zero's location, but the tape ends before we hear her give the details, which leads into the next game, Phantom Pain.
All three main games feature Sequel Hooks as part of their Segmented Endings, unlocked via 100% Completion. Yes, even Corruption, though it's supposed to end the trilogy. In the first two, the Big Bad reveals that she's Not Quite Dead, and in the third, a mysterious ship follows Samus's to parts unknown.
Metroid Fusion left an even more Egregious one: What the hell is Samus going to do now?
Mortal Kombat 9: The ending reveals that Shinnok is ready to perform his act in Mortal Kombat 4 after the timeline has been altered, and generally, the heroes' side have been in a worse condition.
Similarly, at the end of Super Mario Galaxy, once you defeat Bowser at the end of the game's final level with all 121 Power Stars, we actually get to see Rosalina thanking Mario for saving the Mushroom Galaxy and bidding him farewell, but after we see her fly away in her spaceship, it's revealed that she accidentally (or purposely) left one of her Lumas behind on Earth. Also, considering the fact that the entire timeline had to be rewritten as a result of the universe being destroyed and reborn, everyone's all now back at square one, and as a result Bowser now wants to take over outer space again, which leads to...
Ninja Blade: This Xbox 360 action title has the hero Ken Ogawa's father cryptically tell Ken to "save your mother" around 3/4ths into the game. After the final boss, Ken mentions to his handler that he has "something to take care of" and is then shown disappearing somewhere in the city... implying that he's off to discover and save his mother whilst explaining nothing.
Oddworld: Stranger's Wrath: Featured this after a double plot twist in the end sequence. After defeating the Big Bad Sekto, you find out that "Sekto" was really the demon you heard about at the Grubb temple earlier in the game, and that Sekto was really the old guardian of the Grubb Tribe, having been brainwashed by a face hugging parasite. When it looks like Sekto is dead, and everything is back to normal, you see the octopus-like Sekto swim down the newly restored river, apparently looking for a new host. Sadly, Oddworld Inhabitants dropped out of the video game business after Stranger.
Overlord: Rather than this game's cryptic The End... Or Is It?, the Expansion PackRaising Hell ends with a fairly straight sequel hook. The Overlord you were just playing is trapped in the Infernal Abyss, possibly forever, but his Mistress is pregnant. Unsurprisingly, the sequel involves you playing as the Overlord's son, trying to undo the Happily Ever After that ensued in the absence of a legitimate force for evil.
Perfect Dark: The prequel Perfect Dark Zero, like Star Wars, ends with Joanna Dark being an agent of Carrington Institute, and she has her first real mission in the original game.
Pikmin: While the second game was rather close-ended, the first had a best ending where several Onions of colors not seen before fly up from the planet — hinting at at least fourteen additional Pikmin types, but this has not been referenced in either sequeland the Onions were later redesigned. The third game also has three on its best ending: the narrator implies that the Drake's initial crash wasn't an accident, the credits (on any ending) end with something crashing on PNF-404 and the Pikmin running to it, and there's a way to view an SOS revealing that Louie was left stranded on the planet again.
Phoenix Wright: Ace Attorney: Justice for All: Unusually has its sequel hook in the middle of the game: at the end of the second case, Morgan Fey, one of the conspirators in the murder, vows revenge. Said revenge plot is put into action in the last case of the third game.
Pokémon XD: Gale of Darkness: Postgame showed most of the bosses that you face through the course of the game (Gonzap, Chobin, Lovrina, etc.) appearing in the Nintendo HardOrre Colosseum. If you manage to defeat them, they all send you friendly emails... bar Ardos, who declares you Cipher's number one enemy, and saying he will resurrect Cipher one day. After nearly 8 years, we're still waiting.
Ends with a run through an industrial-like mass of corridors and vents until we see a room holding the promised cake, a buffed-up Companion Cube and some spheres in the background. Suddenly, their "eyes" glow a bright orange one by one, before a claw arm puts out the cake candle and floods the room in darkness.Then herVillain Songplays...
Professor Layton: The games have these in the form of pictures that appear after the end credits. These pictures all relate to the next game in line for the series. The only exceptions are Unwound Future, which doesn't have one such picture, and Miracle Mask, which goes Up to Eleven by replacing the picture with a full-blown cutscene that not only ties this game with Last Specter and Eternal Diva, but also sets the stage for the sixth game.
The end of this game has the campers all going home and Raz and Lili sadly separating...only to suddenly reveal that the head of the Psychonauts (revealed to be Lili's father has been kidnapped by a dangerous enemy, and both kids fly off with Sasha, Milla, and Oleander to rescue him. Despite the obvious hook, the creator is unsure if there will be a sequel, given the first game's poor sales but cult status.
Schafer has recently stated that he will make a sequel in the future, but only if his upcoming game The Cave sells well.
Re VOLUTION: Jack goes after the magnate guy, and on the final level, in the very end, we see a car fly away. The ending cutscene shows Jack just standing there, and then Marcus, the resistance leader, comes with his car, says it's over Jack, let's go, they go away, and then the staff roll goes by. However, a sequel has never been made.
Shining Wisdom: Ends with the Valley Fairy using her powers to revive the protagonist, which is against the rules, so she's banished to a labyrinth for eternity. After the credits roll, Princess Satera says that Mars went on a new adventure to save the fairy. Said adventure was never made but plenty of other Shining games were.
Snatcher: The PC88 and MSX2 versions ended after the death of the Benson Snatcher, with the mystery of the Snatchers still unsolved. This was not an intentional sequel hook, but a cut-off point before the third and final act, which was not included in those versions due to time constraints. The later remakes for the PC Engine and Sega CD added the missing act to the game.
Sonic Heroes: Ends with Shadow and Omega looking over the corpse of Metal Sonic and Shadow contemplating his revival. Although the hook for Shadow the Hedgehog was obvious, the fact that Sega set up the ending to keep Metal Sonic alive for a later game and not utilize him since then outside of the Sonic Rivals games is a bit baffling. (Metal Sonic was supposed to be a primary enemy in Sonic 2006 but his role was cut. He does not make a resurgence as a primary villain until Sonic 4 Episode II, which is chronologically earlier than Heroes.)
Space Quest II: The end of this game had Roger Wilco defeated Vohaul and destroyed his base. Wilco, having escaped the base using an escape pod, he has no idea where he is and the pod's depleting life function. All he can do is to hibernate in the cryo bed only to be resolved in Space Quest III.
Splinter Cell Conviction: Has one, though it might take some Fridge Logic to notice: Reed's plan may be foiled, but Megiddo is still out there.
In Spyro: Shadow Legacy the game ends with Spyro preparing for another attack from the Sorcerer sometime in the future, implying he's not done yet. Considering thetwoContinuity Reboots that came to pass after this game, this sadly seems like this won't be happening, at least anytime soon.
System Shock 2: SHODAN is seemingly defeated by the player character, but there is a final scene showing two other survivors of the Von Braun as they make their escape in an escape pod. One of them, Rebecca begins acting strangely and starts speaking in SHODAN's voice! "What's the matter Tommy, don't you like my new look?" Sadly there has never been a direct sequel other than the "spiritual sequel" Bioshock games.
Blacklist ends with the Big Bad revealing that there are a dozen countries supporting his terrorist group. Also, in the co-op campaign, Fisher and Briggs recover the Not Quite Dead body of Kestrel from Conviction's co-op campaign and move him to the Paladin's medical bay.
Super Robot Spirits: After beating Levi, she reveals that she is a puppet of Commander Gozzo. Gozzo thanks Levi for her efforts and intends to commence his invasion of Earth.
In the ending Lostbarrel and Sawatari are still on the run and being fought by Skull Force.
Elder Gods Kurou and Al are going to entrust their son to regular Kurou and Al.
Nyarlathotep is still unfought.
Cao Cao's tactician Sima Yi's face portrait goes from pink to red and he begins facing to the right like an enemy.
Tachyon: The Fringe: A slightly more obscure example, which can be missed if the player does not pay attention to in-game news reports. One of these near the end of the game announces the invention of Tachyon Wave Generators, which will eventually allow gates to send ship throughout the galaxy. Unfortunately, Novalogic never made a sequel.
Thief: The first two games end with these. The third game ends with what could be considered the exact opposite: a Book Ends.
Time Crisis: Razing Storm: The true ending of the arcade mode ends with the protagonists defeating the Giant Space Flea from NowhereTrue Final Boss only to find that they are too late to save their allies and that most of them have been either killed or taken prisoner. Going against your commander's orders to mount a rescue mission to save your remaining allies, the game ends as you and your team head out to save the other team.
To the Moon: Has this in the form of a stinger in which Neil appears to take out a bottle of painkillers and gulp it down before leaving with Eva, implying that he's either addicted or dying. It also has a checkmark appear next to "Episode 1: To The Moon" afterwards.
The Trail Of Anguish: Ends with something happening to your character that will allegedly be explained in the sequel. That was in 2001...
Turok 3: Shadow of Oblivion: Ended with a post-credits scene that ended with Adon leaving her post on the Council of Voice to try and save Joshua Fireseed. The Council of Voices is then seen appointing a mysterious figure to ensure she doesn't succeed. Acclaim Entertainment intended to continue the story in a future sequel. The company went belly up in 2004 though and the Turok game license went to Touchstone Games who promptly rebooted the whole Turok story. It's very unlikely that this ending is never going to be resolved.
Valve Software: This company has had and continues to have an illicit affair with this trope. Half-Life ends with Gordon being saved by the mysterious GMan he sees at several points in the game, put into storage for "future assignments", as does Half-Life 2 (the latter of which resulted in much fandom rage). Episode One ends with Gordon and Alyx caught in a gargantuan explosion, Episode Two ends just before an expedition to the arctic (and just after a devastatingPlayer Punch) and it is all but certain Episode Three will end similarly. Coupled with the Portal example above, it could be they do it just to troll everyone.
Viewtiful Joe: Being a videogame about adventures that takes place inside movies almost invokes this trope at the end of the games.
Wild Woody: At the end of the game, Lowman tells Woody they'll be back next time the world needs saving, and Woody says that would only happen if they sold a zillion units. Being that this was the last Sega CD game at a time when people were moving on to the Playstation and Sega Saturn, it's understandable why the game didn't sell well enough for a sequel.
Ends with Apocalypse viewing the outcome through a monitor.
The Spiritual Successor to that series Marvel Ultimate Alliance ends with a shot of Galactus plotting his revenge on Earth's heroes for stealing his planet-eating devices, and The Stinger revealing that Black Widow was The Mole after all. These all end up being subverted in the sequel: the Galactus incident is said by Thor to have occurred offscreen between the two games, and the second hook appears to have been completely forgotten when you meet the character in question.
Sonic the Hedgehog 2 gains one retroactively in the 2013 remake. If you clear the game with all seven Chaos Emeralds, you will see the wreckage of the Death Egg plumet towards Angel Island, followed by Eggman angrily stomping on the ground with the wreck of the final boss mecha laying in the background. Then a certain pair of eyes appears in a hole in the bushes (in homage of the Sonic the Hedgehog 3 boxart)...
Double's ending in Skullgirls turns out to be one, or in this case a True Story Hook for that matter.
Lambda and Bern: We'll meet again… when something else cries.
KateModern special "Precious Blood" ends with "Precious Blood: 10:30PM", which shows that Terrence is still alive and has killed the Watcher.
At the end of "The Last Work", Julia swears revenge on the K-Team, and some of them say they still want to fight.
The lonelygirl15Grand Finale "The Ascension" is followed by a short surprise video revealing that Lucy is still at large.
Subverted in the Homestar Runner cartoon, DNA Evidence. In the end, it turns out that Strong Sad had the DNA Evidence all along, and then laughs maniacally... and then it turns out that Homsar was there, watching him. Somebody unfamiliar with Homestar Runner would guess he'd tell everybody the news, right?
At the end of The Cartoon Man, both Roy and Karen are cartoonified, while Simon and Valerie get sucked into the Second Dimension. Both plot points play a major role in the follow-up, which itself ends on a major Cliff Hanger.
Dusk's Dawn: We never see what happened to the antagonist, or when the protagonists went to Celestia. However, a new production hasn't been made in years, so it's either been abandoned or stuck in Development Hell.
In Jackie Chan Adventures, after Jade destroys Shendu with one of his own Talismans, Uncle reveals that when an evil is destroyed, a new evil can fill the void, possibly being even more dangerous. The next season deals with Shendu's siblings forcing his spirit (which survived his body's destruction, likely due to the Sheep Talisman or demons naturally become spirits once they die), to take advantage to this void (via an ancient artifact), by using it to release them from their otherworldy prison so they can reconquer the world.
Subverted in Superman: Brainiac Attacks; after Superman finishes pummeling Brainiac's body into scrap, the chip that remains of the original Brainiac is seen ominously blinking amidst the wreckage... until Superman's fist comes down on it, smashing it to pieces.
Played straight in Superman: Doomsday, though: Lex Luthor, having been seemingly killed by the Superman clone earlier in the movie, turns up in a body cast at the end, musing over whether or not Superman is really impossible to destroy.
It did technically lead to Sequel SeriesThe Legend of Korra... but it takes place over 70 years in the future and most of the former cast is dead. The first episode even trolls the audience about the hook, with a character asking about it and the explanation being cut off.
There's also The Promise, a graphic novel Interquel trilogy set one year after the end of the War; in first installment, we discover the end of the conversation started by the above hook - which answers absolutely nothing. It even ends with the exact same sequel hook, only Zuko is now asking Azula about Mom instead of Ozai. Thankfully, the next comic interquel, The Search, has this plot hook as its central premise, so we'll finally get some closure.
And then The Search saddles us with some more: Azula has escaped, and it's unclear whether she'll be redeemed. Also, Zuko and Mai are still broken up, despite Korra showing us that he had kids.
Subverted in Danny Phantom with the episode The Ultimate Enemy, where the Big Bad is shown to be contained, but not entirely defeated, as he was trying to bust out... But he never showed up again. (This was the result of Executive Meddling, canceling the show before they could go through with their plans to bring him back.)
Justice League set up its second season as possibly the last, so they ended it in a truly epic finale with the watchtower base being destroyed. At the end and after Hawkgirl resigns from the League, Superman asks what they are going to do now, which Batman replies with "We rebuild." This leads into Justice League Unlimited, but was enough to be considered And the Adventure Continues.
Batman: The Animated Series did this all the time, particularly in any episode introducing a new villain. There would always be a line at the end in which Batman suspects he hasn't seen the last of the new foe. Perhaps most blatant is the ending to the Ra's Al Ghul two-parter, in which Ra's falls into the Lazarus Pit and is presumed dead, but the final shot shows a hand rising up out of the pit while maniacal laughter is heard.
Freddie as FRO7 had a huge one at the end with Freddie's evil aunt escaping and him getting called over to Washington D.C. There was in fact, already a sequel in the works, but it got shelved when the movie didn't do well and the American release cut half the hook out.
In the U.S. Acres episode "Orson Goes on Vacation", Orson says he'll be on vacation for a week soon, and he asks Wade to be in charge again, but he refuses, a possible nod to "Temp Trouble", even though he was actually gone for two weeks in that episode, possibly because in a scene we weren't shown, he called them in the middle of his vacation to tell that he was going to have an extra week off. The person "in charge" in that episode is Aloysius Pig.
It's not possible both episodes exist at the same time or connected since there was too many different scenes and mixing an old episode to a newer one doesn't fit Roy and Wade's Character Development of their friendship.
Or maybe it took place in the future. This isn't the only time it's happened-the episode where they imagine it's summer during the winter took place a year after the episode had aired, because Wade says his family did something brave every 10 years, and the next time he would do this was in 2004. Said episode aired in 1993.
Speaking of Aloysius Pig, in "Kiddie Korner", we have this little gem:
Orson Pig (singing): We'll bring to you, when we're back next time...
Aloysius Pig (spoken, as he's being hit with pies): HELP! HEEELP!
Orson Pig (singing): Something more wholesome than a nursery rhyme! note Mark Evanier had planned a fourth Aloysius episode, but it was scrapped because CBS wanted budget cuts to the show, and the show's creators didn't want the show to get budget cuts, despite it being CBS' #1 kids' program at the time.
My Little Pony: Friendship Is Magic. The story normally takes place in such a way that any episode can happen any day, but Season 3's premiere ended like this, with Princess Celestia nodding at Princess Luna, who magically summons a book with starsandswirls on the cover.
The season 3 finale (which incidentally pays off said Starswirl sequel hook) definitely is trying to draw you in for season 4. Twilight turns into an alicorn and is now a princess of Equestria. According to the writer's twitter, she considers this episode the first in a 3-parter.
Considering season five was announced, plenty in Twilight's Kingdom Part 2. Such as the whereabouts of Scorpan in all of this, what new powers the rainbow elements entail and how Ponyville will now function as a kingdom, not to mention how Discord's completed reform will be displayed.
BIONICLE: The Legend Reborn ends with Mata Nui and the other heroes discovering that uniting the settlements of Bara Magna (literally, by pulling them together) creates a Humongous Mecha and that the patterns on a stray coin and on the shield of a defeated Skrall soldier depict a map. They set out to find where it leads, with Mata Nui's friends determined to accompany him... and the toy-line got canceled, the sequel scrapped, so the story had to be wrapped up in a comic in which Mata Nui left his friends behind due to the page-limit.
Taz-Mania: In one episode, Molly brings a kitty home and the kitty torments Taz behind Molly's back. In the end, the kitty held a sign saying "I'll be back". A later episode did feature the cat returning.