Fadl ibn Isa^{[note 1]}, also known as Fadl II, was a prince of the Al Fadl, an Arab dynasty that dominated the Syrian Desert beginning in the 13th century. Between 1311 and 1317, he served as amir al-ʿarab, which gave him authority over the Bedouin tribes of northern Syria on behalf of the Mamluk Sultanate.

Fadl was a son of Isa ibn Muhanna, the chieftain of the Al Fadl clan, a branch of the Tayyid tribe of Banu Rabi'ah. Beginning with Isa, members of the Al Fadl became the hereditary holders of the office of amir al-ʿarab (commander of the Bedouin) on behalf of the Mamluk Sultanate. After Isa's death in 1284, Fadl's brother Muhanna became amir al-ʿarab with iqta'at (fiefs) in Salamiyah, Palmyra and elsewhere in Syria. When Muhanna fell out with the Mamluk sultan an-Nasir Muhammad in 1311/12 and defected to the Mongol Ilkhanate, the sultan appointed Fadl in his place as amir al-ʿarab.^[1][2]

Though Fadl appeared to oppose Muhanna's defection, the 14th-century Arab historian, al-Umari, noted that the two brothers cooperated in playing the Mamluks and Ilkhanids off of each other for their own interest.^[3] He wrote "they were agreed at heart, but openly they were otherwise".^[3] Muhanna was restored as amir al-ʿarab in 1317. The following year, Fadl visited Abu Sa'id, the son and successor of the Ilkhanid ruler Öljaitü, to give him a present of Arabian horses in Baghdad.^[4] Soon after, it was reported that the Bedouin tribes of al-Ahsa and Qatif drove Fadl out of the region of Basra south of Baghdad.^[4]

Muhanna was stripped of the post and exiled with his branch of the family in 1320, after which he was replaced by Muhammad ibn Abu Bakr, a distant relative.^[4] In 1322, Fadl was appointed to the post for the second time.^[4] During a visit to Salamiyah in 1324, it was apparent that Muhanna still held sway with the Bedouin in Syria while Fadl was the nominal emir who received a government salary.^[4] In 1328, Fadl gave Muhanna's son Sulayman substantial sums after the latter defected from the Ilkhanids and agreed to submit to Mamluk authority in al-Rahba.^[4] Fadl continued to rule the Bedouin, at least in name, until 1330 when Muhanna was restored.^[4] Muhanna died in 1334 and Fadl likely died in the few years before or after Muhanna's death.^[4] The office of amir al-ʿarab remained hereditary within the Al Fadl clan, but was primarily held by direct descendants of Muhanna.^[5] On some occasions, Fadl's direct descendants held the office,^[6] such as his sons Isa (r. 1342–1343) and Sayf (r. 1343–1345, 1347–1348).^[7]