Eliya XII (Syriac: ܐܠܝܐ / Elīyā, d. 1804) was Patriarch of the Church of the East, from 1778 to 1804, with formal residence in Rabban Hormizd Monastery, near Alqosh, in modern Iraq. His birth name was Ishoyahb, and he was the elder son of priest Abraham, who was brother of the previous patriarch Eliya XI (1722-1778). In 1744, Ishoyahb was consecrated as metropolitan, and designated as presumptive successor (natar kursya) by his paternal uncle, patriarch Eliya XI, who died in 1778, and Ishoyahb succeeded him, as patriarch Eliya XII. His tenure was marked by a prolonged rivalry with his pro-Catholic cousin Yohannan Hormizd, who also claimed the patriarchal throne. In 1804, Eliya XII died and was buried in the Rabban Hormizd Monastery, as the last patriarch of the senior Eliya line.