Big Damn Heroes/Western Animation

"Pariah: *holding Danny and Vlad in his hand, both knocked out* Ghosts and humans! Is there no end to this day's surprises? Valerie: Hey, stoneface! Surprise! *shoots him in the face*"
 * In Phineas and Ferb The Movie: Across the 2nd Dimension, this happens a few times. The first is Candace-2 saving Phineas, Ferb, Perry, Dr. Doofenshmirtz, and Candace from a lava pit after they were being sent to their doom. She rides a giant lawn gnome, smashing into the Mecha-Mooks and throwing the Other Dimensioninator remote to Phineas, which he catches.
 * She then gets apprehended by Doof-2, and is sent to jail. But, Jeremy-2, Phineas-2 and Ferb-2 bust her out.
 * Next, in the film's climax, Perry comes to the aid of his fellow animal agents fighting off Doof-2's Mecha-Mooks. Phineas rescues Perry afterward. Finally, the kids come to their aid,.
 * Perry (and Doof somewhat) serves as this in "Phineas And Ferb Get Busted".
 * Transformers Beast Wars has too many of these to list, generally set up by cutting to the good guys headed towards where they're needed, then cutting back to their destination and letting a scene play out until it's a good time for it to be interrupted by weapons fire. The best example of the trope occurred in "Coming Of The Fuzors, Part 2", when the Maximals are outgunned and literally surrounded. When it looks like they're done for (Megatron says, "Finish it."), the wall of the Maximal baseship blows open to reveal the new-and-improved Optimus Primal, Back from the Dead and ready for a fight.
 * The standard formula for old Mighty Mouse cartoons. It would go like this: the villain (often Oil Can Harry or some other evil cats, but not always) would show up, terrorize one or more victims (usually mice, often a whole city of them) for a while, until something happened to alert the hero (who may have been asleep or otherwise occupied at his moonbase or underground HQ) causing him to spring into action, diving out of the sky with his signature "Here I come to save the day!" and pummeling the bad guys black and blue.
 * Transformers: Full of moments like these, mostly when a character is either first introduced, or appeared to be at death's door previously. One of the best examples has to be the episode "Key to Vector Sigma" where.
 * In fact, Optimus Prime's entire fight scene against the Decepticons and Megatron from the 1986 Animated Movie is a Big Damn Heroes moment. This is acknowledged when Kup says "Optimus did it. He turned the tide".
 * Avatar: The Last Airbender: "The Boiling Rock" has.
 * Also, in "Sozin's Comet":
 * If Appa is not with the group in a battle scene, then when he shows up it is pretty much guaranteed to be a Big Damn Heroes moment.
 * Zuko saves Iroh from being crippled by Earthbenders early in Book 1. They then proceed to mop the floor with them.
 * And in the first episode of season two, just as Zuko is about to be pwned by Azula, Iroh returns the favor.
 * Happens here and there in Danny Phantom.

"Booster: I just hope we're in time! Buzz: It wouldn't be a real rescue if we were too early."
 * Also comes up in The Fairly OddParents a few times. In fact, it's the first thing we see Crash Nebula doing.
 * The second Teenage Mutant Ninja Turtles cartoon has two such moments: the first occurs in "City at War", when Raphael, who had abandoned the turtles after offered to join forces with The Foot, returns for the final battle with Splinter in tow. The second occurs in "The Day of Awakening", when Cody, who had been left behind on Earth, burst into Moonbase Bishop to save the turtles from Sh'Okanabo.
 * Splinter gets one of his own in the first battle with the Shredder, though given it was Shredder who  it makes sense he'd want a piece of the guy.
 * Buzz Lightyear of Star Command episode "The Return of XL" hangs a lampshade on this practice.

"Morgan: Bender's brain lost in the master in pile, and it would take some sort of giant, mechanical, atomic-powered sorting machine to find him. Hermes: You rang?"
 * The opening title sequence of the animated G.I. Joe movie definitely counts. So awesome that it overshadowed the rest of the film.
 * From Futurama: "How Hermes Requisitioned his Groove Back"

"Groundskeeper Willie: Hey! Wolfie! Put down that hors d'œuvre! It's time for the main course!"
 * In The Simpsons, when Bart is being mauled by a wolf (on school grounds, why not) when in steps Groundskeeper Willie, shirtless and ready to kick ass.

""I AM BACK MOTHERFUCKER!""
 * In the season 3 premiere of Metalocalypse, a Corrupt Corporate Executive was trying to force Dethklok to sign a new contract advantageous to him. Nathan was just about to put his signature on it
 * Later that season, when most of the band is captured by an evil sentient robot with a bomb inside it, and Ofdensen is powerless to help (possibly), Pickles pulls this trope off after resolving to Take a Third Option to fall off the wagon and save the band at the same time.

"Batman: (Completely Deadpan) Batman to all points. I could use some air support. Since I can't fly. At all...Now would be good."
 * In an episode of Rocky and Bullwinkle Bullwinkle refuses to put out the fuse of a bomb until the last moment because "Heroes always arrive in the TA-DA! nick of time."
 * Bunnies get to be Big Damn Heroes in Watership Down, when Hazel and his runners lure a Big Damn Dog to the warren, just in time to save Bigwig's life by decimating Woundwort's troops.
 * Invoked in Justice League. Batman is falling without a parachute after ejecting from the Batplane, and is saved by Superman at the last moment.

""Get your claws off my grandson, Vilgax!""
 * This happens a lot in Jonny Quest. One example would be in Manhattan Maneater, when an amoral hunter is about to shoot a white tiger. Just before he pulls the trigger, a gangster steps in the way and refuses to back down. And another happens not a minute later, when the tiger leaps to attack - only to be shot by a tranquilizer, thanks to Race and Dr. Quest who just made it to the scene.
 * Subverted on Jimmy Two-Shoes, when Beezy is being forced to marry the Weavil Princess. First, Heloise bursts in, demanding the wedding stop...only for her to realize it wasn't the McPherson wedding and dismiss herself. Then Jimmy comes in to try and stop it, only for the wedding cake to distract him. The marriage goes through,.
 * In the 1982 animated film Heidi's Song, Peter the goatherd and his animal friends crash their way into the basement as Heidi is fighting off the rats. Complete with the "That's What Friends Are For" melody playing in the background, no less.
 * Bob in ReBoot gets to do one of these right when the Web Riders are about to slaughter everyone on the Saucy Mare. But instead of fighting the Web Riders he orders them to stop, having gained their trust offscreen.
 * Teen Titans: Way, way too many to list, considering it's a show about heroes. There are a few notable moments, however:
 * Red X, of all people, has one of these when he shows up out of nowhere Just in Time to prevent Robin from falling to his death by snatching Robin out of thin air and tossing him to safety on a catwalk.
 * Believe it or not, Scooby Doo gets one in episode 10 of Mystery Inc. He  Words cannot describe how awesome it is. Watch it here, starting at 2:55
 * Possibly a nod to Shaggy and Scooby's Big Damn Heroes moment in Scooby Doo and the Alien Invaders.
 * Ben 10: Grandpa Max has seven words for you:


 * Green Lantern Emerald Knights: The entire Corps is collectively moving a planet toward their enemy using all their willpower, but it's not enough. And then, who shows up via portal but the Green Lantern who "doesn't socialize": Mogo.
 * Frequently in Thundercats 2011 but most notably:
 * Deconstructed in "Omens Part One" when Lion-O, Tygra and Cheetara attempt to save some stockaded Lizard prisoners from abuse, only to turn the Powder Keg Crowd of Thunderian Cats into an Angry Mob in the mood for a Vigilante Execution, triggering a brawl which Lion-O's father Claudus has to stop. He is none too pleased that his son's been protecting Lizards.
 * Played straight in "Omens Part 2" during the siege of Thundera with Claudus and Tygra saved by the Super Speed Speed Blitz of the Clerics, then by Lion-O toting Sticky Bombs, when the pair are twice-surrounded by Turncoat General Grune and his Lizard-manned Walking Tanks.
 * And again in "The Song of the Petalars", when the cats look hopelessly outnumbered and about to die, who should arrive to say them but  Made even more awesome by the fact that he was declared as a dead hero is the opening episode.
 * Code Lyoko is the epitome of this. They're five teenagers fighting against an evil AI who wants to rule the world and can virtual monsters into the real world.
 * A special shout out goes to
 * In the season one Season Finale of Star Trek: Lower Decks, the Cerritos crew is clearly in their Darkest Hour; while Bolier has managed to destroy the Pakled vessel, Shaxs sacrificing himself so that Bolier doesn't go with it, it seems it all was for nothing because three more Pakled ships have shown up. Mainer - who is temporarily in command because every other officer is hurt or unconscious - is about to give the order to abandon ship, when out of the blue, they are hailed by another ship. It's none other than the U.S.S. Titan, Riker's ship. After Riker cajoles Mariner for "starting the party" without him, the theme music from Star Trek: The Next Generation starts to play and the far superior flagship easily dispatches the Pakled vessels, causing the villains to panic and retreat. One of the most awesome scenes in the series.