List of Ottoman titles and appellations in the context of "Agha (title)"

The Ottoman Empire developed over the years as a despotism with the Sultan as the supreme ruler of a centralized government that had an effective control of its provinces, officials and inhabitants. Wealth and rank could be inherited but were just as often earned. Positions were perceived as titles, such as viziers and aghas. Military service was a key to many problems.

The expansion of the Empire called for a systematic administrative organization that developed into a dual system of military ("Central Government") and civil administration ("Provincial System") and developed a kind of separation of powers: higher executive functions were carried out by the military authorities and judicial and basic administration were carried out by civil authorities. Outside this system were various types of vassal and tributary states. Most of the areas ruled by the Ottomans were explicitly mentioned in the official full style of the sultan, including various lofty titles adopted to emphasize imperial rank and show the empire as being "successor-in-law" to conquered states.

Kethüda (Ottoman Turkish: صدارت كتخداسی; Turkish: Sadaret Kethüdası; Persian: کدخدا), often corrupted to k[y]ahya or kehya in daily speech, was an Ottoman Turkish title meaning "steward, deputy, lieutenant". It derives from the Persian word katak-khvatai ("master of a household", later "chieftain, headman").

The term originated in medieval Persia. Under the Ilkhanids, the term kadkhuda (Persian: کدخدا) referred to a village elder who acted as its representative towards the government, and later, under the Safavids, their duties included the collection of taxes and administration of their village or town. From Persian practice it spread to the Seljuk Turks of the Sultanate of Rum, and is first attested in Ottoman usage in the 15th century in the sense of an "authorised deputy official". Accordingly, the term is found across a wide variety of official institutions and offices, both in the central and in the provincial administration, where the kethüda served as a deputy to the agha or re'is in charge of a department or unit or a provincial governor (beylerbey or sanjakbey). By far the most important among them was the deputy of the grand vizier, the sadaret kethüdası; the kethüda yeri supervised the timariots in the provinces, and was also found as a title in the Janissary corps; and the kapı kethüdası was the permanent representative maintained in the Ottoman capital, Constantinople, by provincial governors, senior viziers, or tributary and vassal rulers like the hospodars of the Danubian principalities.