| Yousef VI Emmanuel II Thomas | |
| Birth Name: | Yousef Emmanuel Thomas |
| Church: | Chaldean Catholic Church |
| See: | Babylon of the Chaldeans |
| Patriarch Of: | Patriarch of Babylon of the Chaldeans |
| Residence: | Iraq |
| Enthroned: | July 9, 1900 |
| Ended: | July 21, 1947 |
| Predecessor: | Audishu V Khayyath |
| Successor: | Yousef VII Ghanima |
| Birth Date: | August 8, 1852 |
| Birth Place: | Alqosh |
| Ordination: | July 10, 1879 (Priest) |
| Consecration: | July 24, 1892 (Bishop) |
| Consecrated By: | Eliya Abulyonan |
Mar Yousef VI Emmanuel II Thomas (August 8, 1852 - July 21, 1947) was the patriarch of the Chaldean Catholic Church from 1900 until his death in 1947.
He was born on August 8, 1852, in Alqosh. An ethnic Assyrian, he studied in the Ghazir Seminary in Lebanon and was ordained priest on July 10, 1879. On July 24, 1892, he was ordained Bishop of Seert, now in Turkey, by patriarch Eliya XIV [XIII] Abulyonan. He was appointed Patriarch of the Chaldean Church on the July 9, 1900, and confirmed by the Holy See on December 17 of the same year. He presided over the Chaldean Catholic Church during World War I and World War II, including the Assyrian genocide, serving as patriarch until his death on July 21, 1947. He succeeded Patriarch Audishu V Khayyath and was succeeded by Yousef VII Ghanima.