For the neighbourhood in Istanbul, see Beylerbeyi.
Beylerbey of Anatolia
Beylerbey (from Beylerbeyi, Ottoman Turkish for "Bey of Beys", meaning "Commander of Commanders" or "Lord of Lords"; originally Beglerbeg(i) in older Turkic) is the Ottoman and Safavid title used for the highest rank in the hierarchy of provincial administrators (all military officers at high ranks, generally pashas.) It is in western terms a Governor-general, with authority over the Governors (often styled Wali) of several vilayets, generally (if not yet made) a Pasha (General), second only to the Grand Vizier. Its equivalents in Arabic were amir al-umara, and in Persian, mir-i miran.
The rank was used (with many different spelling variants) initially for very large parts of the empire – all of Anatolia and Rumelia – but in later centuries the title was devaluaed by extending it to the governors of various much smaller Ottoman eyalets.