Sayf ad-Din Qawsun ibn Abdullah an-Nasiri as-Saqi (1302 – April 1342), commonly known as Qawsun (also spelled Qausun or Qusun) was a prominent Mamluk emir during the reigns of sultans an-Nasir Muhammad (r. 1310–41), al-Mansur Abu Bakr (r. 1341) and al-Ashraf Kujuk (r. 1341–42). He came to Egypt as a traveling merchant in a Mongol caravan and after his arrival met Sultan an-Nasir Muhammad, who purchased him as a mamluk. In a few years, Qawsun rose through the military hierarchy, attaining the highest Mamluk military rank of amir mi'a muqaddam alf (emir of one hundred [mamluks], commander of one thousand [soldiers]) and becoming one of the top emirs of the sultan. His adulthood at purchase and quick promotions was atypical of Mamluk emirs, who were usually purchased as children and underwent long and arduous training to attain their high ranks and positions. Qawsun's favorable situation was attributed to his physical appearance and an-Nasir Muhammad's pursuit of a power base composed of outsiders to counter the influence of the existing mamluk factions, including his own.
Following an-Nasir Muhammad's death in 1341, his son al-Mansur Abu Bakr, Qawsun's favored choice, succeeded him as sultan. Abu Bakr's attempts to rule in his own right were stymied by Qawsun, who had him arrested two months into his reign and later executed in November. In al-Mansur Abu Bakr's place, Qawsun installed an-Nasir Muhammad's infant son, al-Ashraf Kujuk as sultan and served as his regent. In effect, Qawsun became the strongman of the sultanate. However, his power was soon challenged by Mamluk emirs in Syria, led by Qutlubugha al-Fakhri, who lobbied for the accession of an-Nasir Muhammad's eldest living son, an-Nasir Ahmad, and the ouster of Qawsun and Kujuk. After the rebels gained control of Syria, some of Qawsun's loyalists defected and revolted against him. In December 1341, Qawsun was besieged in the Cairo Citadel and surrendered. An-Nasir Ahmad became sultan shortly after and had Qawsun, who was incarcerated in Alexandria, executed.