What is the name of the Zoroastrian holy spirit that personifies goodness?

The Zoroastrian holy or bountiful spirit associated with goodness is Spenta Mainyu.

Spenta Mainyu is an Avestan term often translated as “Holy Spirit,” “Bounteous Spirit,” or “Creative Spirit.” It represents the beneficent, life-giving aspect of Zoroastrian theology and is closely connected with Ahura Mazda, the Wise Lord and supreme deity. Through this spirit, goodness, creativity, and the proper order of existence are expressed.

The concept appears alongside a powerful contrast: Angra Mainyu, the destructive or hostile spirit. Zoroastrian moral teaching presents human beings as choosing between the forces that support Asha—truth, right order, and righteousness—and those that promote falsehood and destruction.

Spenta Mainyu should not be confused with the Amesha Spentas as a group. Vohu Manah means Good Mind, while Asha Vahishta concerns righteousness or truth; both are distinct divine principles. Scholars and Zoroastrian traditions differ over whether Spenta Mainyu is a separate hypostasis of Ahura Mazda or Mazda’s creative aspect, but the stored answer remains the standard one.