The Sabbateans (or Sabbatians) are a variety of Jewish followers, disciples, and believers in Sabbatai Zevi (1626–1676), an Ottoman Jewish rabbi and Kabbalist who was proclaimed to be the Jewish Messiah in 1666 by Nathan of Gaza.

Vast numbers of Jews in the Jewish diaspora accepted his claims, even after he outwardly became an apostate due to his forced conversion to Islam in the same year. Sabbatai Zevi's followers, both during his proclaimed messiahship and after his forced conversion to Islam, are known as Sabbateans.

In the late 17th century, northern Italy experienced a surge of Sabbatean activity, driven by the missionary efforts of Abraham Miguel Cardoso. Around 1700, a radical faction within the Dönmeh movement, led by Baruchiah Russo, emerged, which sought to abolish many biblical prohibitions. During the same period, Sabbatean groups from Poland migrated to the Land of Israel. The Sabbatean movement continued to disseminate throughout central Europe and northern Italy during the 18th century, propelled by "prophets" and "believers". Concurrently, anti-Sabbatean literature emerged, leading to a notable dispute between Rabbi Jacob Emden (Ya'avetz) and Jonathan Eybeschuetz. Additionally, a successor movement known as Frankism, led by Jacob Frank, began in Eastern Europe during this century. Part of the Sabbateans lived on until well into 21st-century Turkey as descendants of the Dönmeh.

Sabbatai Zevi was a Sephardic ordained rabbi from Smyrna (now İzmir, Turkey). A kabbalist of Romaniote origin, Zevi, who was active throughout the Ottoman Empire, claimed to be the long-awaited Jewish Messiah. He was the founder of the Sabbatean movement, whose followers subsequently were to be known as Dönmeh "converts" or crypto-Jews.

In February 1666, upon arriving in Constantinople, Sabbatai was imprisoned on the order of the grand vizier Köprülüzade Fazıl Ahmed Pasha; in September of that same year, after being moved from different prisons around the capital to Adrianople (the imperial court's seat) for judgment on accusations of fomenting sedition, Sabbatai was given by the Grand Vizier, in the name of the Sultan of the Ottoman Empire, Mehmed IV, the choice of either facing death by some type of ordeal, or of converting to Islam. Sabbatai seems to have chosen the latter by donning from then on a turban. He was then also rewarded by the heads of the Ottoman state with a generous pension for his compliance with their political and religious plans.

Sabbatai's conversion to Islam was extremely disheartening for the world's Jewish communities. In addition to the misery and disappointment from within, Muslims and Christians jeered at and scorned the credulous and duped Jews.

In spite of Sabbatai's apostasy, many of his adherents still tenaciously clung to him, claiming that his conversion was a part of the Messianic scheme. This belief was further upheld and strengthened by the likes of Nathan of Gaza and Samuel Primo, who were interested in maintaining the movement.

Many within Zevi's inner circle followed him into Islam, including his wife Sarah and most of his closest relatives and friends.^{[citation needed]} Nathan of Gaza, the scholar closest to Zevi, who had caused Zevi to reveal his Messiahship and in turn became his prophet, never followed his master into Islam but remained a Jew, albeit excommunicated by his Jewish brethren.