Rule 63

[1] It began to see general use in fandom communities as a term to refer to both fan-made and official gender flips of existing fictional characters.

Prior to the creation of Rule 63, gender flipping was popularized in video games in the 1990s by the finishing move of Darkstalkers character Demitri Maximoff, a vampire.

Called the "Midnight Bliss", it involved tossing a rose at a character to transform them into a helpless maiden and completely drain them of life energy.

[3] It lists two statements: The trope, originally seen primarily unofficially, later became more widely disseminated in popular culture, with critics stating that it had been "recognized by Hollywood".

[6] However, it has also been used by critics to refer to official characters who are gender-swapped versions of older characters or fictional beings, such as Number Six from Battlestar Galactica being a "sexy female" version of a Cylon Centurion,[7] and the female main cast of the 2016 reboot of Ghostbusters.