In an eighth-season episode of 24, Jack Bauer goes to assault Novakovich's safehouse, but the entire scene is skipped. The viewer only sees the aftermath (Novakovich and all but one of his guards dead with blood all over the place).
During the sixth season terrorists finally succeeded in setting off a nuclear device in Los Angeles, something other terrorists had tried without success in the second and fourth seasons... yet we see nothing of the blast itself beyond a flash and a mushroom cloud in the distance, and nothing of the aftermath other than a nearby neighborhood being evacuated and Bauer having to rescue the occupants of a helicopter which was knocked out of flight by the EMP generated by the blast.
This is spoofed in an episode of Stargate SG-1. The team is on top of a steep cliff with the Stargate on a hill about 50 stories below. Said hill is full of Goa'uld ships, cruisers, troopers, everything you can think of, and "We only have thirty seconds to make it!" before the time-dilation field activates and traps them on the planet. Cut to the heroes back on earth emerging from the Stargate: "Oh, that wasn't so hard.". We then cut back to the real team (the previous scene was from Martin's movie), who point out how stupid that was, as there was no way they could have escaped in thirty seconds even if the valley hadn't been filled with Jaffa. Martin decides to revise the time limit to thirty-eight seconds, because thirty is a round number, which seems too arbitrary.
In "Family" O'Neil tracks an informant into the Goa'uld palace and takes him down. The Jaffa arrive and order the palace sealed. The scene then cuts to the next morning at the rest of the team's hideout, and O'Neil comes barging in wearing a Serpent Guard's armor and helmet, leaving it up to the audience to figure out how the hell he got the armor and escaped.
In the second season of Heroes, we hear an awful lot about the legendary adventures of samurai Takezo Kensei. When we finally meet Kensei, and find out that Hiro has to help him live those adventures, it's not unreasonable to assume that the adventures will actually be, y'know, seen, right? One episode actually starts in the middle of a giant samurai battle, then goes back to talk about the leadup to the fight, then goes directly to the aftermath.
The fight between Sylar and Peter (only heard from behind a door) in "Five Years Gone".
Sylar vs. Peter and Nathan in the Volume 4 finale. Fifteen seconds or so of blue flashes and sound effects while Claire struggles to get in...almost exactly consistent with the Sylar vs. Peter fight in "Five Years Gone".
Buffy and Angel, reunited after she returned from the dead! It must have been intense! Well, yes, apparently it was. She said so. But that was all she said about it, and the encounter wasn't shown on either of their respective shows (probably because they aired on different networks).
More of a parody of this trope than anything else, as Whedon had been hinting at an "epic non-crossover" between the two shows ever since Buffy switched networks. The joke was that while the two shows had crossed over in previous years, this was no longer possible with Buffy on UPN.(until the networks came to agreement and did crossovers anyway.)
Lampshaded in a Buffy comic book story which tied in with the episode. Only, instead of showing us what happened, it's about the supporting cast WONDERING what happened. Everyone lays out wacky fantasy scenarios, but in the end Buffy still doesn't tell them what really happened.
Turned Up to Eleven and parodied in the Buffy season 3 episode "The Zeppo": The gang is fighting what is described as the worst threat they have ever faced, an Eldritch Abomination bent on destroying the world. This is a barely-seen background plot. The main plot is Xander learning an Aesop about confidence. Double-parodied in that Xander's subplot is also an Offscreen Moment of Awesome for all the other characters in a The Greatest Story Never Told fashion, as he's running around trying to get out of the way of the out-of-context fallout from the main plot while chasing down a gang of undead juvenile delinquents bent on blowing the Hellmouth wide open. He decides not to tell anyone else about this, as he now knows full well that he is made of awesome, without validation from anyone else.
In the Fifth Season Penultimate Episode, We have the Big Bad, Glory the HellGod, engaging in a epic against an army of Modern Day Knights in order stop her from obtaining Dawn... or we can assume that, as we watch Buffy viewing the battle helplessly through a barrier.
Willow and Tara's duet about dishwashing. Xander and Anya's dance with coconuts.
Giles singing and playing his guitar in the hotel. The room service chaps joined in on that one.
Another one from Giles in the season 5 episode "Tough Love." Giles, Willow, and Anya capture one of Glory's minions and are about to interrogate him for information. Giles tells Willow and Anya to get some rope to tie him up, and the minute they turn around, the camera focuses on them, and we hear a Sickening Crunch and the minion painfully and frantically agrees to tell them everything. Giles' response to their questions?
HBO's Rome. Any battles the characters are going to, they either get shipwrecked or we only get to see some blurry images (save for the episode "Phillipi", which shows the titular battle in full). Of course, action costs money!
Except for the season 2 episode "Philippi" where 15 minutes in they gear up to begin the battle, and you assume they're just going to skip it like every single other battle, right? No, the rest of the episode is the Battle of Philippi in all of its glory (which is pretty glorious as it's two battles in real life condensed into one for the show).
The Battle of Actium, a battle that, depending on how your count those these things, is still a contender for largest naval battle ever, is depicted in its entirety with a scene of Mark Anthony fleeing in a row boat with smoke in the background.
Antony's friends-romans-countrymen speech after Caesar's funeral singlehandedly turns the Roman people against the conspirators and installs him as the sole ruler of the city. We only hear a description of the scene told by one very minor character to a slightly-less-minor character, and a few later references by others who were there.
Probably one of the worst offenders in recent history is Enterprise's series finale. The whole episode builds up to Captain Archer's final speech that will inaugurate the creation of the Federation. He steps up to the podium, goes to say his first words...and the camera cuts to Troi and Riker looking on before shutting the program down moments later. The cast themselves repeatedly took shots at the episode in interviews during filming.
Many episodes of Enterprise ended with the crew resolving the week's plot offscreen, even if it was something people would have liked to see. This included delivering ambassadors, resolving complex negotiations, defeating the enemy or various character moments that could have been interesting or cool. Instead, most of the resolutions are explained via Archer's log near the end of the episodes.
In the first season of Gossip Girl, Serena's mother takes her to meet the parents of the boy she "killed", something she was so wrecked with guilt over that she fled New York to become a different person. It takes place completely offscreen.
At the end of Season 2, Georgina gets everyone's money back from Poppy after Serena's former friend's ponzi's scheme robs half of the up east side, but we never find out how. She just drives off in her limo, and when she returns at the end of the season, she has the money back.
Star Trek: The Original Series has this in "The Enterprise Incident", where the supposed Romulan prisoners involved in an exchange pull disruptors on Scotty. Scotty just gives them a disapproving look. Later we learn that they're safely in the brig, the episode having skipped over Scotty giving the two of them an epic beatdown.
we never see the Telepath War or most of the Drakh War even though other characters vaguely refer to it all the time, leaving us only with some of the fallout. The details get expanded on somewhat in the spinoff books, but it's still not actually shown.
In "Believers" Ivanova and a Red Shirt go out in Cobras to escort a damaged passenger liner to Babylon 5. Ivanova chases and destroys a raider ship, then her scanner shows dozens more raiders approaching. We cut away as Ivanova has an Oh Crap moment. Later she and the liner arrive at the station with her fighter (in Garibaldi's words) having taken enough damage to put it in the shop for a week. She pretty much laughs it off, leaving the audience to imagine the presumably epic dogfight for themselves.
The Last Great Time War on Doctor Who. It could be argued that it's one chapter of Doctor Who where less is more and nothing could really do it justice, but still, if it was done right, on a proper budget, that could have been the most iconic moment of New Doctor Who. Check out Ten's brief description of it in "The End of Time".
However, Russell T. Davies (who came up with the concept of the Time War) has gone on record as saying that what happened in the Time War is impossible to depict with modern technology, and that's part of the reason it's never shown.
Came close to being shown in the audio drama Dark Eyes. Also many fans think the 50th anniversary will show this.
Infamously done in The Invasion. Halfway through the serial, the UNIT commanders decide it's about time they rescued Professor Watkins from Vaughn's men. Cut to a scene in which some soldiers are talking about what an epic and dangerous operative that was, and that they're lucky Watkins is now safe in their custody.
Smallville, season 8 builds up an epic confrontation with Doomsday, a being that can easily kill Clark and would need special tricks to defeat. The finale has them finally fighting: Clark air-body checks Doomsday into the some facility the League has rigged with explosives. The explosives are set off, and Doomsday is buried underground. We see how it happens, but this trope is VERY much still in play as we do not see 1) how Clark managed to survive (he even Lampshades this), nor 2) any actual fight beyond Doomsday punching Clark a couple times and the aforementioned air-body check. Then it cuts to the next day. Clark mentions offhand as part of the dialogue that he beat Doomsday, but we never see how.
A more minor example is when Clark's Alternate UniverseEvil Twin shows up. Earth-1 Clark is trapped in the other universe, leaving the others to deal with Earth-2 Clark on their own. The fight seems to start with only Tess and Lois, and by the time our Clark gets back, Watchtower is almost destroyed, the two of them and Oliver (who showed up offscreen) are beat to heck and using kryptonite weapons, yet are somehow still alive.
Has happened more than once in Home and Away. Like the story that introduced Peter, where Leah was held hostage and Dan was trying to rescue her...but by the time we came back from commercial, Peter had beaten him to the punch. It's possible that this was done so as to keep the timeslot, but still, pretty damn irritating.
The NCIS: Los Angeles episode "Random on Purpose" had Abby Scuito from the original NCIS guest starring. When she gets kidnapped, mention is made of the rest of Team Gibbs coming to help. However, they are never seen in the episode. When Abby does talk to them, she is by way of a video screen, with the camera on Abby from behind the screen, probably due to the unavailability of the NCIS cast. Made worse by the fact that Gibbs is always at his most Badass when Abby is in trouble.
At the end of the NCIS episode "Frame-Up", Abby takes down Chip, her lab assistant who had framed Tony for murder and hog-ties him off-screen.
Another episode, Bloodbath, has a hitman out to kill Abby. The team tracks down the van that she got carried off in, and arrive just in time to see that she has just finished tasering the crap out of the guy.
In Mighty Morphin' Power Rangers, we only see bits and pieces of the epically-epic universe-spanning battle with the forces of good and evil 10,000 years ago that Zordon and his contemporaries keep referring to. In fact, many Power Rangers incarnations are minor resurgences of much larger battles; "X,000 years ago, there was a a planet/galaxy/universe-spanning war we don't have the budget to show you much of, and now one guy from that war just got un-canned and only has enough power to send monsters one by one" is the setup for as many series as not.
The epic wars only get more epic as the same numbers get used for "X,000 years ago." 10,000 years ago when everyone remotely connected to Lord Zedd was having their heyday, and Zordon was a master wizard kicking ass and taking names, and Earth was involved to some degree, it turns out the original Dai Shi, the three Overlords, and eight Phantom Beast Generals and their Phantom Beast Warriors were out, at their full power, and waging all-out war against humans. 3,000 years ago, Earth had to deal with the Orgs and Shimazu while the rest of the galaxy was dealing with Scorpius. 20 years ago, the Nighloks busted out as they apparently do with some regularity, while at the same time, the forces of the Underworld were tearing apart the dimension next door (mostly unnoticed by humans.) Countdown to Destruction is a taste of what it had to have been like. See Great Offscreen War for a full list.
Power Rangers Samurai saw Scott from Power Rangers RPM come and visit. Over the course of the episode, most of the Samurai Rangers are briefly sent into RPM's universe and they report meeting the other RPM Rangers, but we never see what happens there.
Happens on Chuck fairly often, for no apparent reason except presumably the special effects budget.
In an important episode of season 3, Chuck and Casey are the Big Damn Heroes coming in to rescue Sarah. Chuck goes to find her and the villain himself, and shortly after he appears, we hear gunfire and explosions in the background. The villain says "I see you brought Casey", and that's all we see of the fight. No Casey blowing things up or beating people up himself, just noise and the villain pointing out Casey's habit of destruction.
In the Season 4 premiere, Chuck is cornered by 10 armed Mooks who already know he's a dangerous guy. Their boss has Sarah and Casey hostage and gives the order, by radio, to kill Chuck. The next thing to come over the radio is Chuck saying something like "Clearly you don't know who I am because you only sent 10 men," in his best Bad Ass voice. Sure, it's funny, but why couldn't we see it?
Also happens on My Name Is Earl in the episode My Name is Alias. Earl is tranquillized by Darnell and his father and taken along on a series of missions, but passes out of consciousness, allowing us to only see fragments of the mission, as we watch from his point of view.
In the Blitzgiving episode of How I Met Your Mother: we are sadly not allowed to see our heroes grease up Lily with butter and slide her down the hallway.
A lampshaded example: Ted refuses to tell his kids Victoria's most embarrassing story, which involves Noodle Implements. After the story is told offscreen, Marshall and Lily react with "That was the greatest story ever."
This trope was used hilariously on Monty Python's Flying Circus, in the episode about the man on a bicycling vacation who winds up in the USSR. (It was one of the few episodes with one ongoing plot throughout the episode.) The vacationer is in the USSR, about to be recaptured by the Soviet army. Then there's a cut to a caption saying "Scene Missing," and then he's safely back in England.
Used deliberately in the first-season finale of The Sarah Connor Chronicles. It would have been amazing to see Cromartie finally bust loose and wipe out two SWAT teams and an FBI agent by himself - the only problem is that there was no money in the budget left for such a scene. Working under the gun, Josh Friedman had a solution: a SWAT officer goes flying out of the second-story hotel room Cromartie is in and falls into a pool, and for the next several seconds, all the audience sees are bodies falling in one after the other. It only cuts back to the aftermath when everyone (save for Ellison) is dead. When asked by his superiors what happened, Ellison can't even give them an answer.
On Bones, the UST that makes up the bulk of the character interaction gets resolved completely off-screen.
Elizabeth R was originally intended to have an epic Spanish Armada scene, but because of the budget, a Courtier ran into the Palace and told the Queen about the Armada.
Kaizoku Sentai Gokaiger has the Legend War, a battle in which every member of every Super Sentai team joins forces to fight off an evil space empire that wants Earth. What we do get to see is cool, but it could have been so much greater. According to Word Of God, before that fight there was a battle where over 100 Sentai mecha and giants took on the invasion fleet, with many being destroyed or killed; they wanted to show this in The Movie but weren't able to. The only indication that this happened is in the opening of the Gokaiger/Goseiger crossover movie, where we see the Goseiger fighting the empire while their destroyed mecha lies in the background.
This happens frequently on Merlin thanks to the year-long Time Skips between seasons. It would have been fascinating to see Morgana discover that Morgause was really her half-sister, start learning how to control her magical powers, sink into the rage and bitterness that epitomizes her character from series three onwards, and finally become the last High Priestess of the Old Religion - but it all happens off-screen.
On Leverage this occurs with the Cross My Heart Job, specifically the events that led to them being in the airport with no resources. Eliot even got into an underwater fight. Also the pilot with Eliot again. Eliot is in a restaurant sipping some coffee while confronting some mooks sitting at a table, the mooks refuse to give him the item he is looking for. The lights go off, there are some muzzle flashes and when the lights come back on Eliot is still standing there sipping coffee and the mooks are all unconscious. Their boss finally hands over the item, which turns out to be a Baseball Card.
Spoofed to hell and back in the net movies for Kamen Rider's 40th anniversary movie. The video discussing Kamen Rider Scissors suggests that his Finishing Move is so awesome it wrecks a restaurant and leaves Kamen Rider OOO's main characters so stunned that afterwards all they can do is childishly play with toys. Of course, in reality, Scissors is regarded as one of the weakest Kamen Riders ever, and his finisher is simply a human cannonball attack.
In The Vampire Diaries, Damon giving blood to Caroline to heal her in 02x01. Especially awesome as this time last year he was compelling her and taking blood from her.
Similarly to the Bones example above, in The X-Files, after seven seasons of waiting, Mulder and Scully's UST is resolved off-screen.
Toward the end of the first season of Glee, Kurt Hummel wins the Cheerios a national championship via singing a fourteen-minute Celine Dion medley. In French. We don't get to see it.
For budgetary reasons, Game of Thrones doesn't show most of its battles, usually just the armies charging in followed by the aftermath. Awesomely averted in the penultimate episode of season 2, Blackwater.
One noticeable example is the Battle of the Fist of the First Men around season 3. Which consisted of The Nightwatch fighting a horde of wights, among them reanimated corpses of animals most notably a fucking reanimated BEAR!!. The Nightwatch was completely crushed and demoralized. But we only get to see the survivors make a grim march back to Craster's Keep.
Occurred in the episode of Frasier where Freddie is about to throw down in a street rules spell-off to win back his title, which then skips to Freddie Niles & Frasier alone in the alley with the reclaimed trophy.
Saturday Night Live plays with this when Steve Martin and Bill Murray spend several minutes exclaiming several variations of "What the hell is that?", as they stand and gawk at some strange (and unseen) object.
In 7.01 of Supernatural, Dr. Weiss catches Dean breaking into his house and threatens him with a shotgun. Dean tells him that he doesn't want to hurt anyone; the doctor says, reasonably enough, that he's the one with the gun. The next scene shows Sam and Bobby coming in to find the doctor bound and gagged in his own kitchen.
Pulling stuff like that is kind of par for the course for Dean. It's just usually we get to see it.
Fusco in Person of Interest gets sent to protect a supermodel from the Armenian mob while John is unable to participate. The episode focuses heavily on John, but gives just enough glimpses of Fusco to know that he managed to somehow hold off a squad of Armenian hitmen by dual-wielding pistols and managed to earn a kiss and invitation for more of a relationship with the supermodel.
The series likes to use this trope to show off how Badass Reese is. A scene will open with Reese casually talking on the phone to Finch, Carter or Fusco and as the camera pans out we see that he is surrounded by 5-6 mooks that are on the ground recovering from the beatdown he just gave them. From previous fight scenes we know how good a fighter Reese is and we are left to imagine what cool thing he did in the fight we did not get to see.
Canadian tv movie Net Worth has Detroit Red Wings player Marty Pavelich sent to the minors for supporting a players union. He later tells his former teammates that he's quitting hockey instead. "[Red Wings General Manager Jack] Adams gives me the news and I said 'Go piss up a rope, Jack.' I finally told him off."
In The Wild Wild West's "The Night of the Golden Cobra" Mr. Singh's partner in crime Col. Mayo informs him that Singh's aides have done a Face-Heel Turn and work for Mayo now, as part of Mayo's plan to do anything to get his hands on the oil under Pawnee land - in the cellar of Singh's palace giving him access to said oil he tells West that he must get rid of the Pawnees or it'll go ill for Singh's daughter Veda - whereupon the aged Mr. Singh arrives wielding a sword and announces "Two Sikh mercenaries have gone to join their ancestors. I expedited their departure." This actually has a good reason for being offscreen given that Mr. Singh's played by Boris Karloff, who was 79 at the time...