History NoOntologicalInertia / LiveActionTV

* In ''Series/StarTrekVoyager'''s two-part episode "[[Recap/StarTrekVoyagerS4E8YearOfHell Year of Hell]]", destroying the Krenim time-ship also reverses all of the changes it made to the timeline. {{Justified|Trope}} by exactly ''how'' it plays out -- the changes were made by a device that can erase items from history (i.e. not just eradicating them at that point in time, but literally rewriting the entirety of history so that whatever it is never existed), and when the ship is destroyed, the time-changing device backfires on itself and erases ''itself'' from history, so everything the device had done is undone because said device never existed.

* In ''Series/StarTrekVoyager'''s two-part episode "[[Recap/StarTrekVoyagerS4E8YearOfHell Year of Hell]]", destroying the Krenim time-ship also reverses all of the changes it made to the timeline. {{Justified|Trope}} because of the whole nature of the situation, which involves a device that can erase items from history (i.e. not just eradicating them at that point in time, but literally rewriting the entirety of history so that whatever it is never existed) as well as the nature of the destruction; when the ship is destroyed, the time-changing device backfires on itself and erases ''itself'' from history, so everything the device had done is undone because said device never existed.

* The vampires of ''Series/WhatWeDoInTheShadows'' widely hold the belief that killing a vampire will also kill all of their descendants. In the season 5 finale, [[spoiler:Guillermo discovers that this is true when Derek is staked, restoring Guillermo's humanity after having just fully turned into a vampire, as well as [[NoImmortalInertia catching up on the last month's worth of aging in an instant]].]]

** Averted in "[[Recap/BuffyTheVampireSlayerS1E6ThePack The Pack]]" (Season 1), though the applicability of the trope is arguable. Xander pretends that he doesn't remember any of his actions after the [[spoiler: hyena]] spirt leaves him (but he really does remember). If memories are ''erased'', that can be this trope. If the possessee was never conscious of the events in the first place, then it's not this trope.

** Averted in "[[Recap/BuffyTheVampireSlayerS2E16BewitchedBotheredAndBewildered Bewitched, Bothered, and Bewildered]] " (season 2). Xander misuses a love spell; even after it's undone, the memory of it widens the growing rift between him and Willow (who had unresolved feelings for him already).

** {{Subverted}} and {{Parodied}} in season 4's "[[Recap/BuffyTheVampireSlayerS4E4FearItself Fear Itself]]". Parodied EVEN MORE when said Fear Demon, who has an ominous depiction in the book's illustration of him, arrives. [[spoiler: He's literally the size of the drawing, and Buffy just stomps him with her foot.]]

** In [[Recap/DoctorWho60thASWildBlueYonder "As The Wild Blue Yonder"]], the [[EldritchAbomination Not-Things]] can assume people's form, mind, and memories, and learn fast, but are so alien they can slip up. One impersonating the Doctor takes off his tie and drops it to try to convince Donna he's not a shapeshifter and his clothes aren't part of him, but later in the conversation she notices the tie has disappeared.

* In [[Recap/DoctorWho60thASWildBlueYonder "As The Wild Blue Yonder"]], the [[EldritchAbomination Not-Things]] can assume people's form, mind, and memories, and learn fast, but are so alien they can slip up. One impersonating the Doctor takes off his tie and drops it to try to convince Donna he's not a shapeshifter and his clothes aren't part of him, but later in the conversation she notices the tie has disappeared.