Fablegender (or Genderfable) is a gender that is strongly connected to mythical beings, and for people who kin with such, like mermaids, unicorns, angels, etc.
History
Fablegender was coined by Tumblr user mightyistrying.
Flag
The fablegender flag was designed by Tumblr user mightyistrying.
References
https://variant-archive.tumblr.com/post/178709543957/ive-coined-a-gender-edit-someone-fixed-it-for