Sayf ad-Din Yalbugha ibn Abdullah al-Umari an-Nasiri al-Khassaki, better known as Yalbugha al-Umari or Yalbugha al-Khassaki, was a senior Mamluk emir during the Bahri period. Originally a mamluk of Sultan an-Nasir Hasan (r. 1347–1351, 1354–1361), he rose through the ranks as the senior emirs Shaykhu and Sirghitmish were eliminated, becoming the amir majlis (lord of the audience, a senior administrative official), and achieving the highest military rank of amir mi'a muqaddam alf (emir of 100 mounted horsemen and commander of 1,000 soldiers). Ties between Yalbugha and an-Nasir Hasan deteriorated and the former had the latter, his master, killed in a violent power struggle in 1361.
After an-Nasir Hasan's elimination, Yalbugha became the most powerful figure in the sultanate of al-Mansur Muhammad (r. 1361–1363), who Yalbugha had a hand in appointing and under whom he served as atabeg al-asakir (commander in chief). His power was tempered by the other senior emirs, namely Taybugha al-Tawil. During these years, Yalbugha built up an enormous mamluk household of his own, consisting of some 3,000 mamluks in 1366, including the future sultan, Barquq. That same year, Yalbugha had Taybugha arrested and consolidated his rule. However, in December 1366, Yalbugha was killed by his own mamluks in a rebellion that was supported by then-sultan al-Ashraf Sha'ban (r. 1363–1377). He is buried in the mausoleum he constructed in Rawdah Island, Cairo.