Wikipedia
Vishtaspa () is the Avestan-language name of a figure of Zoroastrian scripture and tradition, portrayed as an early follower of Zoroaster, and his patron, and instrumental in the diffusion of the prophet's message. Although Vishtaspa is not epigraphically attested, he is – like Zoroaster also – traditionally assumed to have been a historical figure, and – again, like Zoroaster – that figure is obscured by accretions from legend and myth.
In Zoroastrian tradition, which builds on allusions found in the Avesta, Vishtaspa is a righteous king who helped propagate and defend the faith. In the non-Zoroastrian Sistan cycle texts, Vishtaspa is a loathsome ruler who intentionally sends his eldest son to a certain death. In Greco-Roman literature, Zoroaster's patron was the pseudo-anonymous author of a set of prophecies written under his name.