Ebu’l-Hayr İsâmeddîn Ahmed b. Mustafa el-Taşköprüzâde (1495-1561) was an Ottoman scholar and teacher. He was the son of Muslihüddin Mustafa Taşköprüzade (1453-1529), judge, teacher and the preceptor of prince Selim (afterwards Selim I). After receiving the first education from his father, he studied in various medreses (religious colleges) in Ankara, Bursa and Istanbul and then became a teacher himself. He taught in Skopje, Istanbul and Edirne, and in 1551 became judge of Istanbul, one of the highest posts in the ulema (jurist) hierarchy. He retired due to bad eyesight in 1554 and spent his last years dictating his works.
Among his books, the most celebrated are aş-Sakâ’ik an-nu‘mâniyya (“The crimson peony”,completed in 1558), a biography of 502 Ottoman sheikhs and ulema and Miftâh as-sa‘âde(“Key to happiness”, completed in 1557), an encyclopedia of sciences, both in Arabic (the latter was translated by his son into Ottoman Turkish, with some additions). He also wrote a short treatise, Risâla fi bayân asrâr al-khilâfa al-insâniyya wa al-saltana al-ma’nawiyya(“Treatise explaining the mystery of man’s caliphate and spiritual sultanate”).