A Replacement Artifact is when the writers of a series decide they don't need one of its devices any more, be it a plot point, a background rule, or whatever, and do away with it, often spectacularly... and then, later on, bring it back under a different name. Often the second attempt is more confusing and less internally stable than the original, yet has an almost-identical effect on the plot.
- In Pokémon, Brock's Casanova Wannabe aspect became the sum of his character as the series went on; he left at the end of the Diamond & Pearl series. In the XY series, we have Bonnie who sometimes tries to set up a beautiful girl with her Big Brother Clemont. Fortunately: A: she doesn't do this with every eligible lady (yet), B: Clemont is suitably embarrassed by this, and C: she's just so young and cute otherwise that she'd be given less leeway for flaws.
- Hypertime was the DC Universe's attempt to bring back the story possibilities of alternate Earths, which it had previously gotten rid of (claiming they had become "confusing") during the Reset Button event Crisis on Infinite Earths. However, this lacked the coherency of the original Multiple Earths rules, and confused far more people than the original ever did. To make things worse (or possibly just more confusing) even Hypertime has been discontinued in favor of "anomalies" from Infinite Crisis. Even the most hardened continuity buffs would be better off adopting the MST3K Mantra.
- DC has adopted the concept of "The Bleed" from Wildstorm, which allows for infinite realities once again, featured prominently in the Wildstorm series' The Authority and Planetary, both created by Warren Ellis.
- While Hypertime as a general structure and editorial direction for the DCU as a whole has fallen out of style, Grant Morrison (one of the originators of the idea, along with Mark Waid) still very much is a believer in it. He deals with the concept in his long-running work with Batman, Seven Soldiers, a run of Action Comics, Final Crisis, and The Multiversity; in Multiversity particularly, he plays with Mythology Gags and Call Backs from throughout the DCU and treats the entire universe's history as still in play, even if it's been retconned out "officially".
- Marvel has hit the halfway mark for this as well, in several of its series. Earth X, Universe X and Paradise X is a story about an Alternate Universe which has some major revelations about the whole of the Marvel Multiverse, which they generally haven't decided to keep. While they always did this to a degree with their Sliding Timescale, they never made it a story feature.
- At one point, Hawkeye purposely blew out his eardrum while he and Mockingbird were under control of a villain's sonic Mind Control. As a result, he was 80% deaf in one ear and used a hearing aid. After a while he temporarily died, as you do, and was resurrected with his hearing restored. However, some fans disliked losing a good example of disabled representation, so eventually he lost his hearing again.
- Sonic the Hedgehog (Archie Comics) killed off Dr. Robotnik in issue #50. He was soon replaced by an alternate dimension Robotnik who had turned himself into a machine and was formerly involved twice with events of this universe before switching to the "Eggman" design of Robotnik of the new games. Then this new Robotnik was made organic again. By aliens.
- In Star Trek: The Motion Picture, the flip-top communicators from the series are replaced with wrist devices, worn on the inside of your wrist, as a logical upgrade in the technology - it's now a little smaller and not something you have to keep taking in and out of your pocket. However, the writers didn't realize until they saw the final product that the gesture of awkwardly holding your arm in the air (not even like the other shows with wrist comms, who have it on the back of the hand - less ergonomically friendly, but a better look) just wasn't nearly as cool as flipping the old communicators open. The flip top communicators were back without comment by the next film, and when TNG went for new communicators again, they made sure that using them looked every bit as good as the flip-open gesture from the then-still-ongoing Original Series movies.
- Harry Potter and the Prisoner of Azkaban introduces Time-Turners. Rowling quickly realized that their existence could cause problems, so two books later she had them all destroyed. Years later, in Harry Potter and the Cursed Child we discover that minor character Theodore Nott eventually makes a new, better Time-Turner that can go farther back and actually change the past. And then, when the plot requires it, we learn that actually Malfoy has a second even-better Time-Turner as well!
- Doctor Who
- Doctor Who didn't write out the Cybermen, but replaced the old ones from a Bizarro World Earth physically located in Earth's solar system with another Bizarro World in another universe. The original Cybermen still exist, and the new series has featured them, in the series five finale and twice in season sixnote — but we only know that by Word of God, because they use the same props as the other type of Cyberman and nobody has ever brought up the difference on-screen. And then the Classic ones are brought back, and given a level or two in badass. Though without the mention of origins.
- In the Classic series, it was intended to retire the Daleks along with William Hartnell, giving Patrick Troughton two Dalek stories ("Power of the Daleks", a very good story with tons of Dalek Fanservice designed to ensure viewers would tune in after the regeneration, and "The Evil of the Daleks", which was intended to be the Daleks's very definitely final death). They go away for several years after that, but attempts to find a replacement Dalek Mascot Mook (the Krotons? the Macra?) failed, the only monsters making as close a cultural dent being the Cybermen and the Autons, and possibly the Yetis. Fan outcry led to the Daleks making a return in "Day of the Daleks", five years after their retirement. Not very long after their return, "Genesis of the Daleks" drastically reinvented the Daleks, updating them by retconning out the more dated backstory elements while fleshing out others, and introducing their leader and creator, Davros, which completely changed the nature of them as a threat.
- The sonic screwdriver falls under this trope. The production team had it destroyed on screen in "The Visitation" after deciding it provided too many easy escapes, and for a while the Doctor made to with bits of string and cricket balls. By the Sixth Doctor's run, however, he starts carrying little doodads, and in "Attack of the Cybermen" he's unapologetically carrying a "sonic lance" that serves both to facilitate escape and as a weapon.
- Even K9 gets this treatment. By the time he leaves the series in "Warriors' Gate", half of K9's function is stunning opponents for the Doctor with a red laser beam from his "nose cannon". So what do we see the Doctor doing in the very next story? Stunning opponents with a green laser beam from an "ion bonder" nicked from Nyssa. The device is used again in "Castrovalva" before getting waterlogged and removed from the story, presaging the destruction of the sonic screwdriver a few years later.
- This was done with Zen and the Liberator in Blake's 7, necessitating a new ship and talking computer in the Postscript Season.
- Heroes killed off precognitive artist Isaac Mendez near the end of the first season. Unable to let go of prophetic art, the next few seasons would be quick to whip out previously-unknown lost works of his (a series of unfulfilled paintings in the second, some comic books and a sketchbook in the third). And gave the same ability to at least three other characters.
- Supernatural: In the first two seasons, the Colt is a unique, legendary Immortal Breaker with a limited number of bullets, the last of which is used in the Season 2 finale. Season 3 introduces a rogue demon who not only teaches the main characters to make more bullets but who also possesses a magic knife that can also kill demons and other immortal entities. Thanks to Serial Escalation, it's found to be ineffective against angels, unlike the Angel Blades that are introduced a few episodes later, and so on...