| al-Mustanjid المستنجد بالله | |
| Khalīfah Amir al-Mu'minin | |
| Succession: | 32nd Caliph of the Abbasid Caliphate Abbasid Caliph in Baghdad |
| Reign: | 12 March 1160 – 18 December 1170 |
| Predecessor: | al-Muqtafi |
| Successor: | al-Mustadi |
| Birth Date: | 1124 |
| Birth Place: | Baghdad, Abbasid Caliphate |
| Death Date: | 18 December 1170 (aged 46) |
| Death Place: | Baghdad, Abbasid Caliphate |
| Burial Place: | Baghdad |
| Spouse: | Zubaydah bint Abu Nasr bin Al-Mustazhir[1] Ghaddha |
| Spouse-Type: | Consort |
| Issue: | al-Mustadi |
| Full Name: | Abu al-Muzaffar Yusuf ibn Muhammad al-Muqtafi al-Mustanjid bi-llah |
| Dynasty: | Abbasid |
| Father: | al-Muqtafi |
| Mother: | Thawus |
| Religion: | Sunni Islam |
Abu al-Muẓaffar Yusuf ibn Muhammad al-Muqtafi (Arabic: أبو المظفّر يوسف بن محمد المقتفي; 1124 – 20 December 1170) better known by his regnal name al-Mustanjid bi-llah (Arabic: المستنجد بالله) was the Abbasid caliph in Baghdad from 1160 to 1170. He was the son of previous Caliph al-Muqtafi.
Al-Mustanjid was born in 1124. He was the son of caliph al-Muqtafi and his mother was an Umm walad named Thawus. His full name was Yusuf ibn Muhammad al-Muqtafi and his Kunya was Abu al-Muzaffar. When Yusuf was a young prince his father became Caliph in 1136. His father ruled for almost twenty-four years until his death in 1160. When his father died, he ascended to the throne. He continued the policies of his father and he also confirmed Awn al-Din ibn Hubayra as his vizier. Awn al-Din had previously served as the vizier to his father. Awn al-Din's[2] Tenure marked the final decline of the Seljuq influence in the Abbasid court (cf. Abbasid–Seljuk war), and saw a flowering of Hanbali learning in Baghdad. Ibn Hubayra was also involved in the conquest of Fatimid Egypt by Nur ad-Din Zangi.[2] One of al-Muqtafi's wives, al-Mustanjid's stepmother, wanted her own son to succeed. She gained over many amirs to her side, and had their slave-girls armed with daggers to kill the new caliph. Al-Mustanjid discovered the plot and placed the rebel son and mother in prison.
Around this time, Fatimid dynasty was at last extinguished, having lasted for 260 years. Their conqueror, Saladin, though himself an orthodox Muslim, initially didn't proclaim the Sunni faith in the midst of a people still devoted to the tenets and practice of the Shi'a sect. But he soon found himself able to do so; and thus the spiritual supremacy of the Abbasids again prevailed, not only in Syria, but throughout Egypt and all its dependencies.
There is little else to say than that this caliph continued to occupy a more or less independent position, with a vizier and courtly surroundings, and supported by only a small force sufficient for an occasional local campaign.