Shams al-Din Ildeniz, Eldigüz or Shamseddin Eldeniz (Persian: اتابک شمس‌الدین ایلدگز‎, died c. 1175–1176) was an atabeg of the Seljuq empire and founder of the dynasty of Eldiguzids, atabegs of Azerbaijan, which held sway over Caucasian Albania, Iranian Azerbaijan, and most of northwestern Persia from the second half of the 12th century to the early decades of the 13th.