- Language: Chagatai
- Alternate names: Chaghatay, Jagatai, Turki, Sart
- Language code: chg
- Language family: Turkic, Common Turkic, Turkestan Turkic, Uyghur-Uzbek
- Number of speakers: No remaining speakers.
Chagatai is an extinct Turkic language that was once widely spoken in Central Asia and remained the shared literary language there until the early 20th century. Literary Chagatai is the predecessor of the modern Karluk branch of Turkic languages, which include Uzbek and Uyghur. Ali-Shir Nava'i was the greatest representative of Chagatai literature.