| Qasim-Khan Zainuddin | |
| Native Name: | قاسِم خان زَينُ الدّين |
| Honorific Suffix: | 31st Da'i al-Mutlaq of the Dawoodi Bohra |
| Image Upright: | 1.2 |
| Death Date: | 1646 CE (1054/56 AH) |
| Resting Place: | Ahmedabad, India |
| Office1: | Da'i al-Mutlaq |
| Term Start1: | 1634 AD (1042 AH) |
| Term End1: | 1646 AD (1054 AH) |
| Predecessor1: | Ali Shams al-Din IV |
| Successor1: | Qutub Khan Qutbuddin |
| Religion: | Islam |
| Sect: | Isma'ili |
| Subsect: | Dawoodi Bohra |
| Background: |
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Syedna Qasim-Khan Zainuddin was the 31st Dai of the Dawoodi Bohras (died on 23 Jumadil Akhir 1054/56 AH/August 25(?) 1646 CE in Ahmedabad, India). He succeeded the 30th Dai Syedna Ali Shamsuddin to the religious post.
Syedna Zainuddin became Da'i al-Mutlaq in 1056 AH/1646 AD.[1] His period of Dawat was 1042–1054 AH/1634–1646 AD. He served five of his predecessors.
Syedna Qasim-Khan's ancestry is traced back to Maulaya Abdullah and Syedi Hasan Feer.
He is buried in Mazar-e-Qutbi in Ahmedabad.