Yahya ibn Abdallah ibn al-Hasan ibn al-Hasan ibn Ali (c. 745/6–803) was an Alid and Zaydi leader who led a rebellion against the Abbasid caliph Harun al-Rashid in Daylam in 792. He was soon obliged to capitulate, but his activity began the spread of Zaydi Islam in the remote mountains of Daylam. After his surrender, he was initially treated with much honour, but Harun remained deeply suspicious of his popularity and intentions, and recalled him to Baghdad, where he spent the remainder of his life in prison. In 802, the Barmakid Ja'far ibn Yahya helped him escape, but he was captured; the event led to the execution of the Barmakids, once Harun's closest companions. Yahya died in prison, probably in 803.