Halil Inalcik believes that Ishak Pasha is created by the confusion between several Ottoman Ishak Pashas (particularly Ishak bin Abdullah and Ishak bin Ibrahim) and Ishak Bey. The confusion can be illustrated with Beltaci's statement that Ishak Pasha was of Croatian or Greek origin and that he served three different sultans.
His first term as a grand vizier was during the reign of Mehmet II ("the Conqueror"). During this term, he transferred Turkmen people from their Anatolian city of Aksaray to newly conquered Constantinople in order to populate the city, which had lost a portion of its former population prior to the 1453 conquest. The quarter of the city where the Aksaray migrants was settled is now called Aksaray.
His second term was during the reign of Beyazıt II. He died in 1497 in Thessaloniki.