Seyid Ali Imadaddin Nasimi (Azerbaijani: Seyid Əli İmadəddin Nəsimi, سئید علی عمادالدّین نسیمی; c. 1369/70 – 1418/19), commonly known as Nasimi[a] (Nəsimi, نسیمی), was a 14th and 15th century Hurufi poet who composed poetry in his native Azerbaijani, as well as Persian and Arabic. He is regarded as one of the greatest Turkic poets of his time and one of the most prominent figures in Azerbaijani literature.

Born around 1369–70, Nasimi received a good education and was drawn to Sufism at an early age. After becoming a faithful adherent of the Hurufism movement, Nasimi left Azerbaijan to spread Hurufism in Anatolia and later Aleppo following the execution of its founder and Nasimi's teacher, Fazlallah Astarabadi. In Aleppo, he gained followers as a Hurufi sheikh but faced resistance from Sunni circles who eventually convinced the Mamluk sultan to order his death for his religious beliefs around 1418–19. Nasimi was executed and buried in a tekke (Sufi lodge) in Aleppo.

His surviving works include two divans (collections of short poems) of poetry in Azerbaijani and Persian, along with some poems in Arabic. Nasimi's poems mainly centre around Hurufism and contain many references to Islamic texts. His poetry combines harmonious melodies and easily understood expressions with more complex topics related to religion. Nasimi had great influence on Turkic literature and influenced many major future poets such as Habibi, Haqiqi (pen name of Jahan Shah), Khatai (pen name of Ismail I), among others. He is also considered the founder of Azerbaijani classical aruz poetry (poetry using quantifying prosody) and ghazal poetry (a form of amatory poetry), as well as the first lyrical poet in Oghuz Turkic classic literature.