The Libu (, R'bw, Ribou, Labu Laguatan, or Lwatae) were an ancient Berber tribe, from which the name Libya derives.

Their occupation of ancient Libya is first attested in ancient Egyptian texts from the New Kingdom, especially from the Ramesside Period. The earliest occurrence is in a Ramses II inscription. There were no vowels in the Egyptian script. The name Libu is written as LBW or RBW in Egyptian hieroglyphs. In the Great Karnak Inscription Merneptah describes how hostilities between Egypt and Libya broke out and how the Libyans were defeated . Ramses III defeated the Libyans in the 5th year of his reign, but six years later the Libyans joined the Meshwesh and invaded the western Delta and were defeated again . Libu appears as an ethnic name on the Merneptah Stele, also known as the Israel Stele Afterward, the name appeared repeatedly in other pharaonic records.

This name Libu was taken over by the Greeks of Cyrenaica, who co-existed with them. Geographically, the name of this tribe was adopted by the Greeks for "Cyrenaica" as well as for northwestern Africa in general. Later, the name appeared in the Hebrew language, written in the Bible as Lehabim and Lubim, indicating the ethnic population and the geographic territory as well.

In the neo-Punic inscriptions, Libu was written as Lby for the masculine noun, and Lbt for the feminine noun of Libyan. The name supposedly was used as an ethnic name in those inscriptions.

Laguatan was the name later Roman authors used to refer to the nomadic tribes in the Cyrenaica area. They have been described as primarily raiders and nomadic, but others consider them a settled group who also raided.

During the Islamic Middle Ages, Ibn Khaldun recorded that the Libu were known as the Lawata.

rabu