Fakir, faqeer, or faqīr (; Arabic: فقیر (noun of faqr)), derived from faqr (Arabic: فقر, 'poverty'), is an Islamic term traditionally used for Sufi Muslim ascetics who renounce their worldly possessions and dedicate their lives to the worship of God. They do not necessarily renounce all relationships, or take vows of poverty, but the adornments of the temporal worldly life are kept in perspective. The connotations of poverty associated with the term relate to their spiritual neediness, not necessarily their physical neediness.

They are characterized by their reverence for dhikr (a devotional practice which consists of repeating the names of God with various formulas, often performed after the daily prayers). Sufism in the Muslim world emerged during the early Umayyad Caliphate (661–750 CE) and grew as a mystic tradition in the mainstream Sunni and Shia denominations of Islam, state Eric Hanson and Karen Armstrong, likely in reaction to "the growing worldliness of Umayyad and Abassid societies". Sufi Muslim ascetics (fakirs and dervishes) were highly influential and greatly successful in spreading Islam between the 10th and 19th centuries, particularly to the furthest outposts of the Muslim world in the Middle East and North Africa, the Balkans and Caucasus, the Indian subcontinent, and finally Central, Eastern, and Southeast Asia. Sufi Muslims have spread throughout several continents and cultures over a millennium, originally expressing their beliefs in Arabic, before spreading into Persian, Turkish, Indian languages, and a dozen other languages.

The term fakir has taken on a more recent and colloquial usage for an ascetic who renounces worldly possessions, and has even been applied to non-Muslims. Fakirs are prevalent in the Middle East and South Asia; they are thought to be self-sufficient and possess only the spiritual need for God. The term is also frequently applied to Hindu ascetics (e.g., sadhus, gurus, swamis, and yogis). These usages developed primarily in the Mughal era in the Indian subcontinent. There is also a distinct clan of faqeers found in North India, descended from communities of fakirs who took up residence at Sufi shrines. 1st Sikh Guru Shri Guru Nanak Dev Ji was entitled with Fakir famously known as "Nanak Shah Fakir". Mowlana Majdeddin Ali Bagher Shah Ne'matollahi in his book "Nasher VA Manshour" states "A mystic is a person whose spine has been broken due to spiritual austerity and who has known his identity. The mystic is absolutely poor and sees nothing but the truth of life."