Atsiz (1098–1156) was the ruler of the Khwarazmian Empire.

Atsiz or Atsız may also refer to: Atsiz ibn Uwaq (died 1079), ruler of Palestine from 1071 to 1079 Ala al-Din Atsiz (c. 1159–c. 1214), Sultan of the Ghurids from 1213 to 1214 Nihal Atsız (1905–1975), Turkish nationalist writer