The 100 takes place 97 years after a nuclear holocaust destroys the Earth. the only susrvivors are the inhabitantss of a space station called "The Ark" which was cobbled together from a dozen other stations in orbit at the time of the war. The plot is about an attempt at recolonization of the Earth's surface using juvenile deliquents.
The 2000s version takes place "after the end" of the Colonial civilization but "before the beginning" of ours.
Colonial civilization was in turn "after the end" of civilization on Kobol, which was in turn "after the end" of civilization on the original Earth. All of this has happened before, and will happen again...
In Cleopatra 2525, humans have been driven from the surface by terraforming machines gone rogue with only a few primitive villages of people who worship Baileys (those same machines). The remaining humans live in vast underground tunnels, fighting one another as well as the terminator-like robots called Betrayers sent by the Baileys to infiltrate the human society. Interestingly, the Baileys have fulfilled their primary programming and have restored the polluted Earth to a lush paradise. Oh, and it's made clear that the humans who live underground have forgotten much of their scientific knowledge and don't quite know how to maintain the tunnels.
In Community epsiode Modern Warfare invokes this trope (and related tropes) For Laughs in a Paintball Episode. After Dean Pelton announced the prize to the school's paintball competition (priority scheduling), almost all of the students destroy each other and their school almost immediately.
The Discovery Channel has a pseudo reality series based on this trope called The Colony, where a group of ten people with varying skills, professions, and backgrounds band together to try and eke out a living in a simulated post-apocalyptic environment. It's filmed in Los Angeles, so you conclude the joke.
Defiance: Between the devastation of the Pale Wars and massive environmental changes caused by malfunctioning Votan terraforming equipment, there is little left of the Earth that existed before their arrival.
In the Doctor Who special "Planet of the Dead", the Doctor arrives on a once-inhabited world which has been turned into a wasteland by an alien invasion.
Also, the entire finale episode of season three explores the Earth a year after the Master has taken control of it.
The Dollhouse episodes "Epitaph One" and "Epitaph Two" take place after massive remote wiping and imprinting is used as a weapon, resulting in the fall of civilization.
The version of Mongo in the Flash Gordon series is this, after a massive explosion known as the Sorrow on one of the moons causes a toxic mineral to rain down on the planet, killing anyone who wasn't able to evacuate and contaminating most of the water. Currently, Mongo has only one city, built atop a clean water source and ruled by a Third World dictator-like Ming "the Benevolent Father" and his Patriot army. All the other tribes (or cantons) live in small villages and are forced to rely on Ming for uncontaminated water. Those who drink the "grey water" go insane and become mutated Deviates. Even many of the tribes suffer from some mutations (some beneficial, such as the Dactyls' ability to soar on winds).
How advanced was the old Mongo civilization? Well, of the three moons that orbit the planet, two were constructed as giant processing stations.
The final season of Fringe; The Observers have completely taken over Earth, and killed most of its population. Those who remain are either on their side (The Loyalists) or fugitives (The Resistance).
In Season 2 of Once Upon a Time Emma and Snow are sent back to the Enchanted Forest where they find that it still exists and there are survivors.
Power Rangers RPM takes place in the third and final year of a Robot War which had, in the earlier years, gone nuclear. The city the series takes place in is explicitly stated to be the only one left on Earth due to its protective shield.
Red Dwarf, though it diverges wildly, being, not after the end of Earth, but after everyone on the spaceship Red Dwarf died, except Lister, who was in stasis. Since it's 3 million years after, the characters assume that all other humans are deceased.
The first episode was actually titled "The End". Take that as you will.
Revolution is set 15 years after all electricity-based technology mysteriously shuts down, causing the collapse of modern tech-dependent society.
As Sliders was premised on travelers going to different dimensions of Earth, they encountered examples of this trope quite often, starting with their first slide together.
The Australian TV series Spellbinder is partly set in an alternate, rustic universe where a reasonably-sized pre-industrial society exists in the midst of an incalculably-large wasteland. It's eventually determined that the Wasteland was created by the Darkness, a nuclear winter created by the Spellbinders' failed attempt at increasing power. As a result, though the Spellbinders have electromagnetic capability in the "Power Stones", they've forgotten how it works, and only really know how to use the stones to power the flying ships and powersuits.
A later season involves traveling to parallel worlds. Several of these have experienced world-changing catastrophes. One takes place after a devastating Robot War, after which humans spend much of their time seeking out and destroying any form of "tech". Another one is cozier but takes place in the aftermath of a deadly plague that wiped out much of humanity. The survivors live only because of a cure that made them immortal but also sterile (i.e. no more new humans).
The Starlost takes place on a generation ship launched from an Earth that was destroyed by some unspecified disaster shortly afterward.
Star Trek itself could be considered an "After The After The End" story - centuries before the show, humans almost destroyed themselves in a nuclear war, but then climbed their way back up to become greater than they were before. The After the End stage, known as the Postatomic Horror, is seen in "Encounter at Farpoint" and Star Trek: First Contact, although the latter is set in one of the less-wrecked areas, rural Montana.
In the Original series episode "Let that Be your Last Battlefield", two dual-toned aliens hijack the Enterprise and force it to take them to their home planet Cheron. When they get there, they discover that a civil war over which sides of the body were what color has wiped out the entire planet's population. In the original version, the planet was shown to be dark mesh of shades of grey, whereas in the remastered episode, lights can be seen on the surface. The Scenery Gorn that passes through the alien's heads suggests that those lights could very well be fires that are still burning, even though the war is long over.
Likewise, it is stated that the Vulcans fought a similar world war which left their planet in ruins (and may explain the desert-like state of the planet). However, they learned to embrace logic and became a major power in the Galaxy. An episode of Enterprise reveals that the war was nuclear in nature and that the losers ended up fleeing the planet, eventually becoming Romulans.
More than one episode involved the Enterprise or Voyager discovering a planet or civilization in this trope.
One Voyager episode actually involved finding a situation like this that was inadvertantly caused by humans... from half-a-galaxy away. During the early days of interstellar exploration (pre-Star Trek: Enterprise), humans sent out warp-capable probes to contact other civilizations and provide them with warp technology. Unfortunately, warp travel involves playing with Anti Matter, and an unprepared species may destroy itself before actually making it into space. As expected, the survivors blame humans.
A recurring sketch in the third season of That Mitchell and Webb Look parodied the concept through an After the EndGame Show, "The Quiz Broadcast"; turns out, having a quiz show after 'The Event' is quite difficult when almost all human knowledge has been eradicated.
The Twilight Zone: Many episodes dealt with survivors of nuclear war. One of the most famous of the lot is "Time Enough at Last," where a neurotic bookworm (Burgess Meredith) survives an apocalyptic nuclear war (only by his sheer luck of being inside a bank vault at the time a random nuclear war breaks out). The man stumbles among the ruins of his hometown, finding he is the lone survivor and then comes upon a huge library of books. (It's all for naught, as he breaks his glasses, and the man — blind without the specs — is unable to engage in a lifestyle of uninterrupted reading.
Two American TV movies made in the early 80s, Testament and The Day After, both attempted to dramatize the horrors of a nuclear war and its aftermath in as realistic a fashion as possible.
The UK equivalents are The War Game (1965, broadcast 1985) and Threads (1984). Both build up to and feature a full-scale thermonuclear holocaust, then - Threads in particular - keep going and get worse. Threads continues to scare those who watched it almost 25 years ago.
These films mentioned here probably take as their basic inspiration the Khrushchev quote about nuclear war that "The living will envy the dead."
Just in case you need more convincing, the second half of "Threads" takes place in a nuclear wasteland - post-apocalypse England, which is populated mostly by ill and dying people, people scared to the point of total paranoia, and corrupt military and government officials. The narrator implies that things are MUCH worse in the US and Russia. Eventually the film fast-forwards to 10 years after the nuclear war, where the new generation is made up of thuggish, possibly retarded teenagers and sickly, often insane adults. And it's implied there may not be a generation after that as a girl's reaction to the baby she's just delivered suggests that it's horribly deformed. The girl herself seems to be so educationally and mentally deprived that she seems almost not to understand what is happening to her as she gives birth and probably has no skills or understanding to enable her to care for a child even if it was healthy. And it's implied she's not unique in this.
Woops! was an actual sit com based on a small group of survivors living in a barn after a nuclear war, and the hijinks they got into.