History Main / GenerationalMagicDecline

** With Feruchemists, while their powers hadn't been deteriorating during the era of Lord Ruler, their total number had due to Lord Ruler trying to explicitly cull all male Feruchemists. However, the Terris people tried to count it with explicit breeding programs. Its only after the events of the first series that the Terris people start commonly intermarrying those of Skaa/Noble decent with allomancer genes, which make full Feruchemists increasingly unlikely. However, Feurchemical powers remain as strong as ever, as Feruchemistry depends on storing one's own power, while Allomancy requires accessing power from Preservation which is what has decayed. Twinborn compounders get around this by being able to turn Allomantic power into individual power.

* In ''Franchise/TheLegendOfZelda'' series, Hylians were originally a race proficient in magic, but over the years the number of Hylians able to use magic has declined to just the Royal family and the Sages.

* ''WebOriginal/AscensionAcademy'' features magical decline heavily in the average power of the people of the world. The majority of the world's magic users dies in the front lines of the Dark War, a brutal conflict that saw the death of over 80% of the world's total population. Very few survived this conflict to pass on their knowledge to the next generation, and currently 300 years later only a handful of individuals are as powerful as the Professors of the Academy who themselves number less than a dozen.

* The Yayoi clan in ''VideoGame/BlazBlue'' was one of the 12 families that formed NOL and were extremely powerful, but they panicked when they started producing children with weaker Ars Magus abilities and started marrying within the family in the belief it would make them stronger. The other members of NOL are noted to be disgusted by this, with the head of the organization even telling them to stop. Things have gotten so bad that Tsubaki is specifically noted to not be the first child of her parents, simply the first to survive early childhood.

** The Nanaya family in ''VisualNovel/{{Tsukihime}}'' used inbreeding to try and prevent this due to their power as an "anything killer" and served the Demon Hunting Organization for generations until they were slaughtered prior to the start of the story.

* In ''Fanfic/WishCarefully'', the Dark Wizards of Voldemort's regime gleefully sign a deal Harry Potter and his allies enact that grants the Death Eaters control of Magical Britain while the Light-aligned wizards, Muggleborns, and [[MuggleBornOfMages squibs]] all leave. It's only then that the Dark purebloods learn the hard way that centuries of close relations has led to increasing numbers of squibs being born and they're growing magically and intellectually weaker over time, so much so that the current crop of magical children can't even pass the traditional sixth-year courses at Hogwarts. [[DeathOfAThousandCuts This is but one of the many gaping flaws in the Death Eaters' idealogy that leads to their society quickly crumlbing apart]].

Compare ImpoverishedPatrician, where a family used to be wealthy but no longer is, and TheMagicGoesAway, for magic's global decline.

** ''LightNovel/TheGardenOfSinners'':

* In ''VideoGame/TheLegendOfZelda'' series, Hylians were originally a race proficient in magic, but over the years the number of Hylians able to use magic has declined to just the Royal family and the Sages.

* In ''Fanfic/WishCarefully'', the Dark Wizards of Voldemort's regime gleefully sign a deal Harry Potter and his allies enact that grants the Death Eaters control of Magical Britain while the Light-aligned wizards, Muggleborns, and squibs all leave. It's only then that the Dark purebloods learn the hard way that centuries of close relations has led to increasing numbers of squibs being born and they're growing magically and intellectually weaker over time, so much so that the current crop of magical children can't even pass the traditional sixth-year courses at Hogwarts. [[DeathOfAThousandCuts This is but one of the many gaping flaws in the Death Eaters' idealogy that leads to their society quickly crumlbing apart]].

* In the ''Literature/WhiteTrashWarlock'' series, it's mentioned that humanity in general is less magically capable in the past. However, for the Binder family specifically, it's because the family knowledge passed down through generations was cut off when Adams great-grandfather hid the family spell book and [[spoiler: became a warlock, feeding off the life force of others]].

*** The Aozaki clan was undergoing this prior to the birth of Touko, who was born with an astounding number of magic circuits considering her parents had none. Later on, in ''VisualNovel/MahouTsukaiNoYoru'' her sister Aoko proved to be a prodigy capable of using the True Magic even though her number of circuits was average at best. When Aoko was chosen to be the family head over her sister the fallout was [[CainAndAbel enormous]].

* In ''Fanfic/WishCarefully'', the result of the Dark Wizards of Voldemort's regime being cut off from the Light side of the world means they've had centuries of inbreeding, which has gradually produced fewer and fewer magically-capable children every generation. In the one Lucius is writing about in the fic, only four such children were born, and they're so weak that they can't even pass the sixth-year courses at Hogwarts because they don't have enough power.