The Pishdadian dynasty (Persian: دودمان پیشدادیان, romanized: Dudmân-e Pishdâdiyân) is a mythical line of primordial kings featured in Zoroastrian belief, Persian mythology and Iranian national history. They are presented in legend as originally rulers of the world but whose realm was eventually limited to Ērānshahr or Greater Iran. Although there are scattered references to them in the Zoroastrian scriptures—the Avesta—and later Pahlavi literature, it is through the 11th-century Iranian national epic, the Shahnameh, that the canonical form of their legends is known. From the 9th century, Muslim writers, notably Tabari, re-told many of the Pishdadian legends in prose histories and other works. The Pishdadian kings and the stories relating to them have no basis in historical fact, however.

According to the Shahnameh, the Pishdadians were the first Iranian dynasty, pre-dating the historical Achaemenids, and ruling for a period of over two thousand years. Their progenitor was Keyumars, the first human and the "Zoroastrian Adam". He was followed by his descendants who, as kings of the world, fought demons and improved the lives of humankind by introducing them to new knowledge and skills. His most renowned successor, Jamshid, established the main elements of civilization, but, as a result of his pride and hubris, was overthrown by the evil tyrant Zahhak. Following a popular insurrection against Zahhak, the throne was eventually restored to the Pishdadians. However, the next king, Fereydun, divided the world between his three sons with his youngest, Iraj, receiving Iran, the choicest portion, after whom it is named. Iraj and his successors aroused the envy of the other descendants of Fereydun, leading to a lengthy feud and series of wars which eventually caused the downfall of the dynasty. The Shahnameh tells how the Iranians, having no confidence in the last of the Pishdadians, replaced them with another mythical dynasty, the Kayanians.

Tabari repeated many of the same stories in his History, with some variations. As with many of the medieval Muslim writers, he intermixed these stories with narratives relating to Quranic figures, and stories of the prophets, to give them a distinctively Islamic perspective.

The stories of the Pishdadian kings have been politically and culturally influential in Iranian society. Both in antiquity and the Middle Ages, ruling dynasties claimed descent from them in order to be imbued with their prestige and political legitimacy. Into the modern era, the tales of the Shahnameh continue to pervade all aspects of Iranian culture and, as part of that, the Pishdadians remain central to Iranians' sense of the roots of their own history and national identity.

The Pishdadian kings are figures in Persian mythology, about whom a number of legends are recorded in Zoroastrian texts, including the Avesta, and in the Shahnameh, a medieval Persian poem recognised as Iran's national epic. From the 9th century, the Pishdadians also appear in Arabic prose works of Muslim writers. The overwhelming evidence is that the existence of the Pishdadian dynasty has no historical basis. The various tellings of their story nevertheless portray them as the first Iranian dynasty ruling a mythical kingdom that existed at a time before the Achaemenids, the first historical Persian dynasty. The etymology of Pishdadian (from Persian: پيشداد, pišdād) is usually thought to mean "those who first promulgated laws". However, an alternative view is that it comes from paradhata, a word from the Avesta, meaning "created before [others]" or "first created".

The most canonical account of the mythical early kings of Iran is provided by the Shahnameh, an epic poem of the early 11th century composed by Abolqasem Ferdowsi, a Persian poet from Tus in Khorasan. Considered to be a globally significant literary masterpiece, the poem is a history of Iran from its mythic beginnings to the Muslim conquest at the end of the Sasanian period, and opens with the story of the Pishdadian kings. Ferdowsi's work was the culmination of a long tradition of oral and written prose and poetry, and the stories he drew on may reach back to Indo-European traditions pre-dating Iranian culture. He is thought to have used both oral and written sources, including, apparently, a now lost prose epic compiled in Tus in the mid-10th century, and which itself was based on a late Sasanian chronicle, also now lost, called the Xwadāy-nāmag. Additionally, Ferdowsi may well have used his own poetic imagination to add to or change the stories, although it is difficult to judge the extent to which he did this. Although Ferdowsi was a Muslim writing for a Muslim audience, the Shahnameh is seen as "non-Islamic" (albeit monotheistic) and partly reflecting a Zoroastrian perspective. Ferdowsi excludes Islamic cosmology and chronology from the Shahnameh and makes the pre-Islamic Persian myths the core message of the epic.

Following the Shahnameh, an Iranian tradition of writing epics about mythological heroes lasted for about 300 years. The only significant one to contain material on the Pishdadians was the Garshasp-nama, which opens with a retelling of some of the stories of the Shahnameh.

The mythical kings of the Shahnameh have parallels with characters in the much earlier Avesta, which likely reached its final form by the middle of the first millennium BCE. However, the Avesta gives only brief references to the characters involved, using different or variant names, with little detail of the myths that later find their full expression in the Shahnameh. These are mainly in the yashts or Avestan hymns. Although these references are brief, it is clear from the context and the way they are presented that they allude to stories very similar to the later, more developed, Zoroastrian tradition. Sitting between the Avesta and the Shahnameh are Middle Persian or Pahlavi Zoroastrian texts, such as the Denkard, the Bundahishn and the Ayādgār ī Jāmāspīg. Although they are nearly contemporaneous with the Shahnameh, they may embed stories and traditions from much earlier sources and provide a link with the ancient Avestan texts. They give more detail than the Avestan references on some of the stories relating to the mythic kings, but still do not provide full narratives in the manner of the Shahnameh. In some instances, the descriptions are at variance with both the Shahnameh and the Avesta.