Sheikh Muhammad-Hasan Abi al-Mahasin al-Janaji al-Ha'eri (Arabic: الشيخ محمد حسن أبي المحاسن الجناجي الحائري; 1875–1923) was an Iraqi poet and politician.

Abi al-Mahasin was one of the leaders of the Iraqi revolution against the British occupation during and after the First World War.

He became Mirza Taqi al-Shirazi's representative, by leading the Revolutionary Council (known as al-Majlis al-Milli; Arabic: المجلس الملي) in 1920.

He later became the Minister of Education in the first national government of the royal reign of King Faisal I after Iraq's independence in 1922.

Abi al-Mahasin wrote a lot of poetry on pan-Arabism, and the glory of the Arabs, and one of his famous lines includes:[2] فمتى تؤلف وحدة عربية وطنيه الإصدار والإيراد ليس العراق بموطني هو وحده فبلاد قومي كلهن بلادي When will there be Arab unity, A patriotic notion of giving and taking.