Hi! I nominated several tales that haven't been included at AO3 before, so I thought to provide links for them and other sources (warning, character name of Hellawes is used in Takarazuka musical based on King Arthur, so it seems to cause some issues).

#1- While I nominated La Morte'd Arthur, as it's avaiable source and tag, I want specifically to focus on one character and chapter/episode, so here are links for them:
-https://en.wikipedia.org/wiki/Hellawes_(sorceress)
-https://kingarthur.fandom.com/wiki/Hellawes_(sorceress)
-https://once-upon-fic.dreamwidth.org/44782.html#comments
-https://www.heritagehistory.com/index.phpc=read&author=morris&book=arthur1&story=perilous

#2- ,,The Last Pearl'' by Hans Christian Andersen :
-http://hca.gilead.org.il/last_pea.html

#3- The Brothers Grimm fairytale ,,The devil with Three Golden Hairs'':
-https://en.wikipedia.org/wiki/The_Devil_with_the_Three_Golden_Hairs
-https://www.cs.cmu.edu/~spok/grimmtmp/022.txt

Thanks a lot for hosting this exchange, and I hope you stay safe and happy in this and following years!