Persians, or the Persian people, are an Iranian ethnic group from West Asia. They are indigenous to the Iranian plateau and comprise the majority of the population of Iran. They have a common cultural system and are native speakers of the Persian language. In the Western world, "Persian" was largely understood as a demonym for all Iranians rather than as an ethnonym for the Persian people, but this understanding shifted in the 20th century.

The Persians were originally an ancient Iranian people who had migrated to Persis (also called "Persia proper" and corresponding with Iran's Fars Province) by the 9th century BCE. Together with their compatriots, they established and ruled some of the world's most powerful empires, which are well-recognized for their massive cultural, political, and social influence in the ancient Near East and beyond. The Persian people have contributed greatly to art and science, and Persian literature is one of the world's most prominent literary traditions both inside and outside of Iran. The regional prestige of their civilization was the basis for the development of many noteworthy Persianate societies, especially among the Turkic peoples, throughout Central Asia and South Asia.

In contemporary terminology, Persian-speaking people from Afghanistan, Tajikistan, and Uzbekistan are known as Tajiks, with the former two countries having mutually intelligible Persian varieties known as Dari and Tajiki, respectively; whereas those from the Caucasus (primarily in the Republic of Azerbaijan and in Dagestan, Russia), albeit heavily assimilated, are known as Tats. Historically, however, the terms Tajik and Tat were used synonymously and interchangeably with Persian. Many influential Persian figures hailed from outside of Iran's modern borders—to the northeast in Afghanistan and Central Asia, and, to a lesser extent, to the northwest in the Caucasus proper. In historical contexts, especially in English, "Persian" may be defined more loosely (often as a national identity) to cover all subjects of the ancient Persian polities, regardless of their ethnic background.

The term Persian, meaning "from Persia", derives from Latin Persia, itself deriving from Greek Persís (Περσίς), a Hellenized form of Old Persian Pārsa (𐎱𐎠𐎼𐎿), which evolves into Fārs (فارس) in modern Persian. In the Bible, particularly in the books of Daniel, Esther, Ezra, and Nehemya, it is given as Pārās (פָּרָס).

A Greek folk etymology connected the name to Perseus, a legendary character in Greek mythology. Herodotus recounts this story, devising a foreign son, Perses, from whom the Persians took the name. Apparently, the Persians themselves knew the story, as Xerxes I tried to use it to suborn the Argives during his invasion of Greece, but ultimately failed to do so.

Although Persis (Persia proper) was only one of the provinces of ancient Iran, varieties of this term (e.g., Persia) were adopted through Greek sources and used as an exonym for all of the Persian Empire for many years. Thus, especially in the Western world, the names Persia and Persian came to refer to all of Iran and its subjects.

Some medieval and early modern Islamic sources also used cognates of the term Persian to refer to various Iranian peoples and languages, including the speakers of Khwarazmian, Mazanderani, and Old Azeri. 10th-century Iraqi historian Al-Masudi refers to Pahlavi, Dari, and Azari as dialects of the Persian language. In 1333, medieval Moroccan traveler and scholar Ibn Battuta referred to the Afghans of Kabul as a specific sub-tribe of the Persians. Lady Mary (Leonora Woulfe) Sheil, in her observation of Iran during the Qajar era, states that the Kurds and the Leks would consider themselves as belonging to the race of the "old Persians".

On 21 March 1935, the king of Iran Reza Shah of the Pahlavi dynasty issued a decree asking the international community to use the term Iran, the native name of the country, in formal correspondence. However, the term Persian is still historically used to designate the predominant population of the Iranian peoples living in the Iranian cultural continent.