The kizlar agha (Ottoman Turkish: قيزلر اغاسی, Turkish: kızlar ağası, lit. '"agha of the girls"'), formally the agha of the House of Felicity (Ottoman Turkish: دار السعاده اغاسي, Turkish: Darüssaade Ağası),[1] was the head of the eunuchs who guarded the Ottoman Imperial Harem in Constantinople.
Established in 1574, the post ranked among the most important in the Ottoman Empire until the early 19th century, especially after the stewardship of the two holy cities of Mecca and Medina and the supervision of all waqfs (charitable foundations) in the Empire came under his purview. The wealth thus amassed, the proximity to the sultan, and the role the harem ladies played in court intrigues ("Sultanate of Women") meant that its occupant had considerable political influence; several kızlar aghas were responsible for the downfall of grand viziers and the accession of sultans. Soon after its creation and until its abolition, close to the abolition of the Ottoman sultanate, the post came to be occupied by Black African eunuch slaves, and hence is also referred to as the Chief Black Eunuch.