Rabih az-Zubayr ibn Fadl Allah or Rabih Fadlallah, usually known as Rabah in French (c. 1842 – April 22, 1900), is a Sudanese warlord and slave trader who establishes a powerful empire east of Lake Chad, in today's Chad.

Born around 1842 to an arabized Nubian family in Halfaya Al-Muluk, a suburb of Khartoum, he first serves with the irregular Egyptian cavalry in the Ethiopian campaign, during which he is wounded.

When Rabih leaves the army in 1860s, he becomes the principal lieutenant of the Sudanese slaveholder Sebehr Rahma.