Idris I (March 12, 1890 - May 25, 1983) was the last King of Libya from 1951 to 1969. Born Sidi Muhammad Idris al-Mahdi al-Senussi, he was the grandson of Muhammad ibn Ali as-Senussi , the founder of the Senussi Muslim sect. He inherited his grandfather's position and at the close of World War I was recognized by the British under the new title Emir of Cyrenaica, a position confirmed by the Italians in 1920.

Politically, Idris spent the early part of his career attempting to negotiate independence for his territory. When that failed, with Mussolini in control in Italy, he went into exile in 1922. Egypt served as his base in a guerilla war against the colonial authorities.

During World War II, Idris supported the United Kingdom and brought the Cyrenaican nationalists to fight alongside the Allies against the Axis, which occupied Libya. With the defeat of the Germans under Erwin Rommel, he was finally able to return to his capital, Benghazi. He was also asked to become emir of Tripolitania, another of the three traditional regions that constitute modern Libya (the third is Fezzan). By accepting he began the process of uniting Libya under a single monarchy. From Benghazi, Idris led the team negotiating with the United Kingdom and the United Nations over independence. Independence was achieved on December 24, 1951, and Idris was proclaimed king of Libya.

To the chagrin of Arab nationalists at home and supporters of Pan-Arabism in neighboring states, Idris maintained close ties with the United Kingdom and the United States, even after they intervened in Egypt during the 1956 Suez Crisis. Another threat to his regime was his failure to produce a male heir to succeed him to the throne. Thus, while the country prospered from its oil fields and the presence of American bases, the future was shaky and the king was now in poor health.

On September 1 in 1969 while Idris was in Turkey for medical treatment, he was deposed by the Libyan army under the leadership of Muammar al-Qaddafi in a bloodless coup. Idris eventually went into exile in Egypt. Idris died in 1983 in Cairo, Egypt.