Ahmad Sanjar (full name: Muizz ad-Dunya wa ad-Din Adud ad-Dawlah Abul-Harith Ahmad Sanjar ibn Malik-Shah) (b.

1085 – d. 8 May 1157) is the Sultan of the Seljuq Empire from 1118 to 1153.

He is initially the sultan of Khorasan until he gains the rest of the territory upon the death of Muhammad I. Clifford Edmund Bosworth notes Sanjar is a Turkic name, denoting "he who pierces", "thrusts".