The Senusiyya, Senussi or Sanusi are a Muslim political-religious Sufi order and clan in Libya and surrounding regions founded in Mecca in 1837 by the Grand Sanussi (Arabic: السنوسي الكبير as-Sanūssiyy al-Kabīr), the Algerian Muhammad ibn Ali al-Sanusi.
During World War I the Senussis fought against both Italy and Britain. During World War II, the Senussis provided support to the British Eighth Army in North Africa against Nazi and Fascist Italian forces. The Grand Senussi's grandson became King Idris I of Libya in 1951. The 1969 Libyan revolution led by Muammar Gaddafi overthrew him, ending the Libyan monarchy. The movement remained active despite sustained persecution by Gaddafi's government. The Senussi spirit and legacy continue to be prominent in today's Libya, mostly in Cyrenaica.