Zalaagra is a Threadwielder, cited as the creator of the “draconics”. Her name is a derivative of the word zalaar (beauty).
It's unclear when Zalaagra seeded her worlds, or even how many she seeded, but it's made clear on several occasions that Earth and Nekenalos allegedly pale in comparison.
Zalaagra's most notable action was letting Valcen live on Sesakanala for many avatar generations and letting him gather Thread there, rather than forcibly evicting him. She's implied to be starkly apolitical, erring on the side of neutrality.