Kadi Burhan al-Din Ahmed (Azerbaijani: Qazi Bürhanəddin, Turkish: Kadı Burhaneddin; died 1398) was an Oghuz. vizier and atabeg to the Eretnid rulers of Anatolia. In 783 AH (1381–1382) he took over Eretnid lands and claimed the title of sultan for himself. He is most often referred to by the title “kadi“, or Islamic judge, his first position under the Eretnids.
Burhan al-Din justified his claim to the throne through descent from the Seljuks: his grandmother was the granddaughter of Kaykaus II. The Eretnid sultanate he inherited had a large Turkmen and Mongol population but also contained many of the older, established urban centers of the Seljuks of Rum and Ilkhanid Anatolia. The sultanate resembled these older states more than the Turkmen beyliks then ascendant in other parts of Anatolia.
The Kadi’s eighteen-year rule was not peaceful. He challenged the Turkmen Karamanids and Beylik of Erzincan and twice fought Kötürüm Bayezid, Jandarid bey of Kastamonu. In 1387, he was defeated by the Mamluks of Egypt. The Ottoman Sultan Bayezid I, accompanied by his vassal the Byzantine Emperor Manuel II Palaeologos, campaigned against Burhan al-Din in 1391. He met his end in 1398 at the hands of the Ak Koyunlu and was succeeded by his son Zayn al-‘Abidin, who ruled for a short time between 1398 and 1399. His türbe, or mausoleum, survives in Sivas.
He was an outstanding poet, who wrote primarily in Persian. Qāżi Aḥmad Borhān al-Din played significant role in the development of the Azeri Turkish poetry.
'Aziz ibn Ardashir Astarbadi, a companion of Kadi Burhan al-Din, wrote a Persian language history of his rule called Bazm-u Razm which was edited by M. F. Köprülüzade in 1928. An analysis and commentary has been provided by H. H. Giesecke, Das Werk des ‘Azīz ibn Ardašīr Astarābādi (Leipzig, 1940).