Báb, Iranian religious leader, founded Bábism (d. 1850)
The Báb, born Sayyed ʻAlí Muḥammad Shírází (; Persian: سيد علی ‌محمد شیرازی; October 20, 1819 – July 9, 1850) was the founder of Bábism, and one of the central figures of the Baháʼí Faith.

The Báb was a merchant from Shiraz in Qajar Iran who, in 1844 at the age of 25, claimed to be a messenger of God. He took the title Báb (; Arabic: باب), meaning "Gate" or "Door", a reference to the deputy of the promised Twelver Mahdi or al-Qá'im. He faced opposition from the Persian government, which eventually executed him and thousands of his followers, known as Bábís.

The Báb composed numerous letters and books in which he stated his claims and defined his teachings. He introduced the idea of He whom God shall make manifest, a messianic figure who would bring a greater message than his own. His ideas had roots in Shaykhism and possibly Hurufism and his writings were characterized by their extensive use of symbolism including the use of much numerical calculations. Abdu'l Baha summarises the Báb's impact: "Alone, He undertook a task that can scarcely be conceived... This illustrious Being arose with such power as to shake the foundations of the religious laws, customs, manners, morals, and habits of Persia, and instituted a new law, faith, and religion."To Baháʼís, the Báb fills a similar role as Elijah or John the Baptist in Christianity: a predecessor or forerunner who paved the way for their religion. Baháʼu'lláh, the founder of the Baháʼí Faith, was a follower of the Báb and claimed in 1863 to be the fulfillment of the Báb's prophecy, 13 years after the Báb's death.