Ali Osman Alhaj (Arabic: علي عثمان; born 1958 in Omdurman, Sudan-February 16, 2017) was a Sudanese composer of contemporary classical music. He lived in Egypt since 1978 and was active in Egypt's contemporary music scene. He also played the guitar, drum kit, and double bass.
He studied with Gamal Abdel-Rahim and Awatef Abdel Karim at the Cairo Conservatoire. He taught music at the Cairo Conservatoire since 1990, and at the Arabic Higher Institute of Music in Cairo since 1999.
He died on February 16, 2017 in Cairo.