Mandaeans (المندائيون al-Mandāʾiyyūn), also known as Mandaean Sabians (الصابئة المندائيون al-Ṣābiʾa al-Mandāʾiyyūn) or simply as Sabians (الصابئة al-Ṣābiʾa), are an ethnoreligious group who are followers of Mandaeism. They believe that John the Baptist was the final and most important prophet. They may have been among the earliest religious groups to practice baptism, as well as among the earliest adherents of Gnosticism, a belief system of which they are the last surviving representatives today. The Mandaeans were originally native speakers of Mandaic, an Eastern Aramaic language, before they nearly all switched to Iraqi Arabic or Persian as their main language.
After the invasion of Iraq by the United States and its allies in 2003, the Mandaean community of Iraq, which before the war numbered 60,000–70,000 persons, collapsed due to the rise of Islamic extremism and the absence of protection against it; with most of the community relocating to Iran, Syria and Jordan, or forming diaspora communities beyond the Middle East. Mandaeans have been forcibly converted to Islam, making them apostates from Islam if they revert back to their religion, thereby risking being murdered. Such Mandaeans have voiced feeling unsafe in any Muslim country for this reason.
The remaining community of Iranian Mandaeans has also been dwindling as a result of religious persecution over the decades. Unlike other religious minorities such as Christians, Jews and Zoroastrians, Mandaeans have no protection from persecution whatsoever, similar to Baháʼís in Iran. By 2007, the population of Mandaeans in Iraq had fallen to approximately 5,000.
There are estimated to be 60,000–100,000 Mandaeans worldwide. About 10,000 Mandaeans live in Australia and between 10,000 and 20,000 in Sweden, making them the countries with the most Mandaeans. There are about 2,500 Mandaeans in Jordan, the largest Mandaean community in the Middle East outside of Iraq and Iran.
The name "Mandaean" comes from the Mandaic word manda, meaning "to have knowledge".