Celestial / Cosmic
"In a Strange turn-it seems the first dragonmarks appeared on the halflings of Talenta. After that the elves begin to speak about marks among their population, the mark of shadow presumably. Those who believe in a 13th mark often bring up the vagueness with which Elven scholars describe these marks. While it is somewhat confusing, we have equally confused and vague accounts from Talenta, so maybe there's just something about these first marks that people don't understand."
Dragonmarked: The Histories of Marks and the Houses built around them by Professor York of Morgrave University