Which Avatar co-creator wrote parts one, three, and four of Sozin's Comet?

Avatar co-creator Michael Dante DiMartino wrote parts one, three, and four of Sozin's Comet.

DiMartino was one of Avatar: The Last Airbender's two creators, alongside Bryan Konietzko, and he received writing credit for three of the finale's four chapters. He wrote part one, “The Phoenix King,” part three, “Into the Inferno,” and part four, “Avatar Aang.” Konietzko also assisted with parts three and four, while Aaron Ehasz wrote part two, “The Old Masters.”

This credit pattern reflects the finale's collaborative production rather than a single-author structure. DiMartino and Konietzko created the series' world, characters, and overarching story, while Ehasz served as head writer and contributed to the scripting process. The finale's writing follows several parallel storylines before bringing them together in the conclusion.

A frequent mistake is choosing Bryan Konietzko because he co-created the series and helped write the last two parts. That credit is real, but the question asks who wrote parts one, three, and four specifically. Jeremy Zuckerman composed the music, while Aaron Ehasz wrote only part two of this four-part finale.