Atsiz, Abbasid caliph (d. 1156)
Ala al-Din wa-l-Dawla Abu'l-Muzaffar Atsiz ibn Muhammad ibn Anushtegin (Persian: علاء الدين والدولة أبو المظفر عتسيز بن محمد بن أنشتكين; 1098 – 1156), better known as Atsiz (اتسز) was the second Khwarazmshah from 1127/8 to 1156. He was the son and successor of Muhammad I.