Ayatollah Mohammad Mahdi Shamseddine (Arabic: محمد مهدي شمس الدين) was a Lebanese Twelver Shia scholar.
[1] Shahid Awwal who was known as Shamseddine, sun of the faith, was ancestor of Muhammad Mahdi.
Allamah al-Shaykh Abdul Kareem Shamseddine was his father and studied at Najaf seminary.
When Mohammad was 12 years old, his father returned to Lebanon but Muhammad Mahdi decided to stay and finish his religious studies.
Grand Ayatollah Abul-Qassim Khoei and Sayed Muhsin al-Hakim were his teachers at Najaf seminary.