Al-Rahba, also known as Qal'at al-Rahba, which translates as the "Citadel of al-Rahba", is a medieval Arab fortress on the west bank of the Euphrates River, adjacent to the city of Mayadin in Syria. Situated atop a mound with an elevation of 244 meters (801 ft), al-Rahba oversees the Syrian Desert steppe. It has been described as "a fortress within a fortress"; it consists of an inner keep measuring 60 by 30 meters, protected by an enclosure measuring 270 by 95 meters. Al-Rahba is largely in ruins today as a result of wind erosion.

Asad ad-Dīn Shīrkūh bin Shādhī, also known as Shirkuh, or Şêrko was a military commander in service of the Zengid dynasty, and uncle of Saladin. His military and diplomatic efforts in Egypt were a key factor in establishing the Ayyubid dynasty in that country.