So, you've got a character with their own series. And they've got a whole supporting cast of characters with similar powers, almost a super-powered family. To make the character more "special", they get rid of all the similar characters.
Inversion of The Chosen Many, where a unique character becomes part of a group of similarly-powered characters. Although a Long Runner (like many comic book series) might go back and forth between the two repeatedly.
- The two most famous examples both involve The DCU. Has happened repeatedly to Green Lantern, and the Reset Button has been pressed every time. The great Power Battery exploded, leaving only a few Lanterns active. ...but then the Guardians were brought back, rebuilt, and recruited new Corps members. ...so a few years later, Hal Jordan went crazy-evil and killed off most of the Corps, leaving Kyle Rayner as the only one with the power. ...until he got a copy of Hal's original ring, which could create new copies, brought back the Guardians, and recruited new Corps members. And so on.
- The biggest Post-Crisis change to Superman was the decision that "last son of Krypton" meant last, as in no other Kryptonians ever, period. General Zod becomes a Russian, Kandor becomes an alien ghetto and thus devoid of actual Kryptonians, and Supergirl becomes... uh, you'd better see that entry for yourself. They've lightened up on that in recent years, without returning to constantly tripping over one more Kryptonian a la pre-Crisis comics (or Smallville), as various writers attempted to reclaim the concepts without hitting the Reset Button -- at least, so fa-.
- Done to the entire Justice Society of America in The Last Days of the Justice Society, to get rid of the extra Flash, extra Green Lantern, extra Hawkman, etc. Naturally, they were brought back a few years later. And then most of them were killed off in Zero Hour just to crank up the drama, leaving Wildcat, Jay Garrick (the original Flash), Ted Knight (the original Starman), and Alan Scott (the original Green Lantern).
- Amazingly, the JSA was rebuilt by three of those four (with Ted Knight retiring permanently and dying at the end of the Starman series), using legacies and the occasional resurrected character. Even then, some resurrected old-school JSA members, such as the first Hourman, who came back during Black Reign, stay retired. The JSA has a lot of legacies.
- During Infinite Crisis, Bart Allen absorbed the entire Speed Force into himself, and became the only Flash-style super-speedster. The ensuing series lasted only 13 issues, and ended in favor of a Flash series by Mark Waid, the guy who pretty much built the previous "Flash Family", focusing on Wally West and his superpowered kids.
- Marvel Comics did this to the X-Men with House of M; millions of mutants all over the world were depowered, except for 198, supposedly chosen at random. Very few characters anyone cared about at all lost their powers, and those who did gained them back pretty quickly. Recently, a new mutant baby has been born, signaling the return of mutants to the wider Marvel Universe.
- The 2005 revival of Doctor Who set up the complete destruction of Gallifrey in its Backstory, leaving The Doctor as the last of the Time Lords, until the Master returned at the end of the third season.
- Unlike most examples of this trope, however, Doctor Who's Legacy Implosion has (a) been reasonably popular and (b) stuck. As for (a), the new series is phenomenally popular, and while the Legacy Implosion isn't the main reason for that it obviously hasn't hurt. And as for (b), the only Time Lords seen in the new series were the Master, and a Shadow Archetype seems like a reasonable exception to a "last of the..." rule, and some others brought back briefly and temporarily by Time Travel. At some point Gallifrey might be brought back, who knows, but six seasons and counting is a longer duration of this implosion than most.
- Batman's True Companions were imploded piece-by-piece, with the exceptions of marketable stalwarts Robin and Nightwing. Orpheus dead, Spoiler dead for dubious reasons, long-time confidant Leslie Thompkins implicated in killing the latter "to teach Batman a lesson", current Batgirl realizing a Face Heel Turn, former Batgirl Oracle bombed out of her headquarters and sent away from Gotham City along with her Birds of Prey team, Onyx inexplicably vanished from the books. Some of these got undone: Steph wasn't really dead, and became the new Batgirl, Cassie turned out to be under mind-control and joined Batman Incorporated as Black Bat, and Babs returned to the Bat-fold as Batman Inc's computer specialist. As of the New 52, Babs is Batgirl again, however the fate (or existence) of the others is currently unknown.
- Aquaman's supporting cast were killed off one by one to add drama to the book and boost sales.
- The Flash suffered this in the New 52. Wally West is who knows where, Jay Garrick is on another Earth, Max Mercury and the Quicks could be either. Bart Allen still exists, but doesn't currently have a real connection to Barry.
- This was the major criticism of Blackest Night (generally well-received otherwise) and Brightest Day. In the former, the number of non-legacy characters who died and stayed dead was exactly one, Tempest, with other casualties including Hawkgirl II, Hawk II, Damage (one of the numerous inheritors of the original Atom's mantle), Gehenna Hewett (half of Firestorm II), and Doctor Polaris II, the last of these only receiving an offhand mention and never actually being shown. Seeing a pattern here? Brightest Day killed off yet another Atom legacy and Miss Martian was presumed dead for a couple issues, too. The fans didn't take any of this particularly well, and it added more fuel to the Epileptic Trees that the DC suits want the Silver Age back.
- As you might notice above, this happens to Hawkman with some regularity, in varying degrees. It never sticks, and only ever makes the Mind Screw of a Continuity Snarl that is Hawkpersons even more tangled.