Sultan Zainal Abidin III Muadzam Shah ibni Almarhum Sultan Ahmad Muadzam Shah II, , (12 April 1866 – 26 November 1918) was Sultan and Yang di-Pertuan Besar of the state of Terengganu from 1881 to 1918.
Succeeding on the death of his father Sultan Ahmad, under his reign Terengganu became a British protectorate by the Anglo-Siamese Treaty of 1909.
In 1911, Sultan Zainal Abidin III issued Terengganu's first constitution.
He died in Kuala Terengganu on 26 November 1918, aged 52, after a nearly 37 year reign and was buried in the Zainal Abidin mosque.