Yahya al-Mu`tasim (Arabic: أبو زكرياء المعتصم يحي بن الناصر; Abū Zakarīyā' Al-Mu`taṣim Yaḥyā ibn An-Nāṣir; died 1236) was an Almohad rival caliph[1] who reigned from 1227 to 1229.
He was a son of Muhammad al-Nasir[2] and brother of Yusuf II, Almohad caliph.
At the death of his uncle Abdallah al-Adil, Yahya was supported by the sheikhs of Marrakesh, but two years later he was turned down by another pretender, his other uncle Idris al-Ma'mun.
At the latter's death in 1232, Yahya renewed his pretenses, but his cousin Abd al-Wahid II was preferred to him.
He was anyway able to keep Marrakesh until his death in 1236, after which the Almohad territories were again united under Abd al-Wahid.