Emetullah Rabia Gülnûş Sultan (Ottoman Turkish: گلنوش امت الله رابعه سلطان; c.1642 – 6 November 1715) was the chief consort of Ottoman Sultan Mehmed IV, Haseki sultan of the Ottoman Empire from 1664 to 1687, the mother of Ottoman sultans Mustafa II and Ahmed III, and the Valide sultan of the Ottoman Empire from 1695 to 1715. She was one of the prominent figures during the era of the Sultanate of Women which spanned for nearly 200 years and ended with her death in 1715. She is considered to be the last powerful imperial consort and Valide sultan in Ottoman history.

Gülnuş Sultan was born in 1642 in the town of Rethymno, Crete, when the island was under Venetian rule, the daughter of a Greek Orthodox priest, and her birth name was Evmania Voria. According to a minor theory, Gülnuş Sultan instead belonged to the Venetian Verzini family which had settled the city.

She was captured by the Ottomans during the invasion of Crete in 1645.

The Ottoman army invaded the island during the Cretan War; she was captured as a very young girl when the Ottomans conquered Rethymno in 1645, taken as a slave and was sent to Constantinople. She was renamed Emetullah Rabia Gülnuş and was given a thoroughly Ottoman education in the harem department of Topkapi Palace and soon attracted the attention of the Sultan, Mehmed IV, and became his concubine. He was famous for his hunting expeditions in the Balkans and used to take her, his favourite, to these expeditions. She was described as a curvy woman with long black curly hair. They had at least six children, among them two sons both of whom became Sultans, Mustafa II and Ahmed III. Ahmed was born in Dobruca during one of the hunting expeditions of Mehmed IV. Her rivalry with Gülbeyaz, an odalisque of Mehmed IV, led to a tragic end.

Gülnûş Sultan's participation in the campaigns during her 27-year haseki period and her knowledge of political developments, her long haseki period together with Hatice Turhan Valide Sultan as the haseki of Mehmed IV and the mother of Prince Mustafa and Prince Ahmed, and her financial power virtually prepared her for the institution of Valide Sultan. She gained value as she served the Ottoman dynasty, and her status as the sultan's favorite shaped her future. Her participation in male-specific activities, such as hunting and campaigns, thanks to her husband's affection for her, gave her advantages unique to male members of the dynasty. She enjoyed these until her death, earning a place in history through the structures she commissioned and her role in politics. In other words, her harem journey, which began as a female slave, turned out to be more advantageous for her as she prioritized service to the dynasty and embraced masculine roles.

Sultan Mehmed had been deeply enamored of her, but after Gülbeyaz entered his harem, his affections began to shift; Gülnuş, who was still in love with the sultan, became madly jealous. One day, as Gülbeyaz was sitting on a rock and watching the sea, Gülnuş slightly pushed her off the cliff and drowned the young odalisque, or according to others she ordered Gülbeyaz's strangulation in the Kandilli Palace. Some writers stress the fact that Gülnuş was a ruthless person, claiming that she attempted to have her husband's brothers Suleiman II and Ahmed II strangled after she gave birth to her firstborn Mustafa, but Mehmed's mother Turhan Sultan had prevented these attempted murders.

Gülnüş Sultan was aware of the political developments of the time. Indeed, Haseki Sultan participated in the Polish War of 1672 and 1673, along with Mehmed IV and Hatice Turhan Sultan. Similarly, in 1682, during the Second Siege of Vienna, Haseki Sultan joined the regiment when they went to Belgrade. The happiest days of Gülnüş Sultan's life as a haseki occurred in the spring of 1675, at the imperial ceremonies held in Sirık Square of the Edirne Palace for the circumcision of her sons and the marriage of her biological daughters. The Zübde-i vekayiat records that during the ceremonial stages of this wedding, Valide Turhan Sultan and Gülnüş Sultan were represented by their chamberlains in the ranks of viziers. The traveler Tavernier, a foreign observer, commented on the importance Gülnüş Sultan placed on this wedding as follows:

"(Mehmed IV's) son was circumcised in a very magnificent ceremony. This prince's mother, a very beautiful woman, requested that the prince's clothing be covered in diamonds to ensure the ceremony would be a magnificent spectacle for both Turks and foreigners. To achieve this, very valuable items from the treasury were destroyed and then everything was taken back to its place.''