‘Izz al-Dīn Abū Sarī‘ ‘Ajlān ibn Rumaythah ibn Muḥammad Abī Numayy al-Ḥasanī (Arabic: عز الدين أبو سريع عجلان بن رميثة بن محمد أبي نمي الحسني) was Emir of Mecca from 1344 and 1372, with interruptions.
Ajlan was born around 707 AH (c. 1307), son of the Sharif Rumaythah ibn Abi Numayy, Emir of Mecca.
In 744 AH (1343/1344) Ajlan and his brother Thaqabah purchased the Emirate of Mecca from their father for 60,000 dirhams. Soon afterwards, Thaqabah went to Egypt in response to summons from Sultan al-Salih Isma'il while Ajlan remained in Mecca. In Dhu al-Qi'dah 744 AH (March/April 1344) he fled to Yemen when he received word that al-Salih had arrested Thaqabah and returned the Emirate to Rumaythah.
In 746 AH (1345) al-Salih summoned Ajlan to Cairo and appointed him Emir of Mecca in place of his father. Before Ajlan returned to Mecca, al-Salih died. His brother and successor al-Kamil Sha'ban gave Ajlan a renewed decree of appointment. Ajlan reached Mecca in Jumada al-Thani accompanied by 50 mamluks, and was proclaimed Emir at the qubba of Zamzam on 18 Jumada al-Thani (c. 15 October) after Maghrib. To secure his power Ajlan expelled his brother Thaqabah to Wadi Nakhlah, and his brothers Sanad and Mughamis to Wadi Marr al-Zahran. In early Dhu al-Qi'dah (February/March 1346) he received word from the Sultan's messenger that his brothers had been arrested in Egypt.
In 747 AH (1346/1347) or 748 AH (1347/1348) al-Kamil released Thaqabah, Sanad, and Mughamis and appointed them co-rulers with Ajlan. Ajlan was briefly ousted by Thaqabah in 750 AH, but he returned from Egypt on 5 Shawwal 750 AH (c. 16 December 1349) and retook the Emirate from his brothers.
In Dhu al-Hijjah 752 AH (January 1352) after mediation from the Egyptian amir al-rakab, Ajlan agreed to rule in partnership with Thaqabah. The following year Thaqabah deposed him. In Dhu al-Hijjah 754 AH (January 1353) after Thaqabah refused an offer to share the throne with Ajlan, the Egyptian amir al-rakab Umar Shah arrested him and designated Ajlan sole Emir of Mecca.
In Muharram 757 AH (January 1356) Ajlan again agreed to share the Emirate with Thaqabah. On 13 Jumada al-Akhir (c. 13 June) Thaqabah deposed him, but when the Hajj arrived (November 1356) Ajlan reentered Mecca and Thaqabah fled. In Dhu al-Hijjah 758 AH (November 1357) the brothers reconciled and Thaqabah returned as co-ruler.
In Jumada al-Awwal 760 AH (April 1359) Sultan al-Nasir Hasan summoned Ajlan and Thaqabah to appear before him but they did not do so. The following month they received word that al-Nasir had deposed them and appointed in their place their brother Sanad and their cousin Muhammad ibn Utayfah. Ajlan proposed to Thaqabah that they each give 400 camels to secure the allegiance of the Banu Hasan and preserve their rule. Thaqabah rejected Ajlan's proposal, and Ibn Utayfah assumed the Emirate when he arrived with Egyptian forces in late Jumada al-Akhir (May 1359).
Ajlan went to Egypt, but upon his arrival al-Nasir had him arrested and imprisoned. In 762 AH (1361) al-Nasir was killed and replaced by al-Mansur Muhammad. Emir Yalbugha al-Umari released Ajlan and had him reappointed to the Emirate of Mecca in partnership with Thaqabah, who was then coregent with Sanad. In Ramadan (July 1361) Ajlan reached Wadi Marr where he met Thaqabah. Thaqabah was ill, and Ajlan did not proceed to Mecca until early Shawwal 762 AH (August 1361), after Thaqabah's death. Upon assuming the Emirate he ousted Sanad and appointed his own son Ahmad as coregent.
In 763 AH (1361/1362) Ajlan conquered Haly Ibn Yaqub, a feat not accomplished by any Sharif of Mecca before him since Abu al-Futuh al-Hasan ibn Ja'far (r. 994–1039).
In 774 AH (1372) Ajlan relinquished full control of the Emirate to Ahmad, though his name continued to be mentioned alongside his son's in the khutbah until his death. He died at al-Jadid in Wadi Marr on Monday night, 11 Jumada al-Ula 777 AH (7–8 October 1375) and was buried in al-Ma'lah cemetery, where a qubba was built over his grave.