The Khalaj (Bactrian: χαλασσ, romanized: Xalass; Persian: خلجها, romanized: Xalajhâ) are a Turkic ethnic group who mainly reside in Iran. In Iran they still speak the Khalaj language, although most of them are Persianized.
Historically, the Khalaj who lived among Pashtuns were slowly Pashtunized. Due to this, the Khaljis of Delhi, originating from Khalaj migrants from Afghanistan into India, were often considered to be Pashtuns by other Turkic nobles. The Ghiljis, one of the largest Pashtun tribes, also derive their name from the Khalaj, and it is likely that the Khalaj initially formed the core of this tribe.