Zeynab Begum (also spelled Zainab or Zaynab; died 31 May 1640) was the fourth daughter of Safavid king Tahmasp I (r. 1524–1576), and considered to be one of the most influential princesses of the Safavid era. She lived during the reigns of five successive Safavid monarchs, and, apart from holding diverse functions, including at the top of the empire's bureaucratic system, she was also the leading matriarch in the royal harem for many years, and acted on occasion as kingmaker. She reached the apex of her influence during the early reign of king Safi (r. 1629–1649). In numerous contemporaneous sources, she was praised as a "mainstay of political moderation and wisdom in Safavid court politics".
Zeynab Begum was born by one of Tahmasp's Georgian wives, a princess named Huri-Khan Khanum. Her date of birth is unknown. At a young age, Zeynab Begum was assigned a guardian (laleh), Shah-Qoli Beg, a high-ranking member of the Shamlu Qizilbash faction. Later, when her father died in 1576 and was succeeded by Ismail II (r. 1576–1577), she was given in marriage to Ali-Qoli Khan Shamlu, a son of Durmish Khan Shamlu. The marriage took place not long before 7 December 1577, but it was apparently never consummated, for Zeynab Begum continued to live in the royal harem in the Safavid capital of Qazvin.
In the ensuing period, Zeynab Begum played a pivotal role in support of her nephew, heir-apparent Hamzeh Mirza. According to a report by Iskander Beg Munshi, Zeynab Begum stood at the head of the royal harem during the frantic civil war that had engulfed the empire in the late 1580s, amidst the Ottoman-Safavid War of 1578–1590. Later, she functioned as one of the most important supporters of the young Abbas (later known by his regnal name of Abbas I; r. 1588–1629) during the war of succession that had commenced during the last few years of king Mohammad Khodabanda (r. 1578–1587).