Ibn Taymiyya, Taqiyy ad-Din Ahmad, 1263-1328, Muslim theologian and jurist. He lived in Damascus after the collapse of the central caliphate to the Mongol invasion from the East, and during the continuous threat of Christendom from the North and West. Influenced by Ibn Hanbal, he was unyielding in his political and religious positions, and was frequently persecuted and imprisoned. A prolific writer, Ibn Taymiyya advocated a doctrine of conservative reformism, stressing the need for communal solidarity. He remains one of the lasting influences on contemporary political Islam, notably on Wahhabiya (see Wahhabi) and Salafiyyah.

Ad-Din is a laqab, a component of some Arabic names, meaning "of the faith." People with this laqab include:

• Jamal ad-Din (astronomer)(13th century), Persian Moslem astronomer
• Salah ad-Din, better known as Saladin (1138-1193), ruler of Syria and Egypt
• Al-Afdal ibn Salah ad-Din (born 1160), son of Saladin and second emir of Damascus
• Nur ad-Din (1118-1174), Zengid dynasty ruler of Syria
• Ismat ad-Din Khatun (died 1186), wife of Nur ad-Din
• Ali ibn Sabr ad-Din (lived after 1344), Governor of Ifat
• Haqq ad-Din II (ruled late 14th century), Sultan of Ifat
• Sa'ad ad-Din II (ruled c. 1400), Sultan of Ifat
• Sabr ad-Din II (died 1422/1423), King of Adal
• Mansur ad-Din (died 1424), Sultan of Adal
• Badlay ibn Sa'ad ad-Din (died 1445), Sultan of Adal
• Muhammad ibn Azhar ad-Din (reigned 1488-1518), Sultan of Adal
• Nasr ad-Din (Lamtuna) (in power 1644-1674), Berber leader
• Jamal ad-Din (disambiguation) - several persons of this name
• Nasir al-Din (disambiguation) includes Nasir ad-Din - several persons of this nameSee also
• Izz al-Din, or Izz ad-Din, honorific title incorporated in certain Arabic names
• Salah ad Din Governorate, Iraq