Endless Witch

Title held by:

Passed from a Beatrice to the next as described in Regarding the Succession of Witches.

The title of Endless Witch has its fundation in "Endless Creation" and is the root of her unmatched, eldless magical power.
~ Beatrice's Titles

When she was joined with the Witch of Origins through Mariage Sorcière, their magical compendium gained an endless span, as well as endless power.
~ Beatrice#Alliance

It's probably safe to say that the formation of this alliance allowed Beatrice to gain the endless power in its truest sense.
~ Mariage Sorcière

The willpower of Certainty is far stronger than the Endless, which just repeats over and over idly...
~ Lambdadelta#Alliance#Tea Party

Endless magic is a folk tale

The origin of the endless magic narrative is a kind of folklore passed down in Kumasawa's family. It pre-dates Kinzo's golden witch narrative and it could have been a source of inspiration for him, or maybe the two concepts were separate until they were merged by Sayo, who was raised in part by both of them.

Maria has contributed her imagination and occult hyper fixation, but she didn't come up with the whole thing like we initially theorized. Maybe "gaining endless power" means entering the public consciousness, and the rokkenjima case was instrumental for that to happen with Beatrice.

Leads:

The magical lore fluff in Regarding the Succession of Witches hints at a long lineage of endless witches, but nothing of the sort exists about the golden witch.
Virgilia, aka. Kumasawa is the previous endless witch, but seemingly not a golden witch.