Khalifa or Khalifah is a name or title which means "successor", "ruler" or "leader". It most commonly refers to the leader of a Caliphate, but is also used as a title among various Islamic religious groups and others. There were four Rashidun caliphs after Muhammad died, beginning with Abu Bakr. The Khilaafat (or Caliphate) was then contested and gave rise to the eventual division of the Islamic Umma into two groups, the Sunni and the Shi'a who interpret the word Khalifa in differently nuanced ways.

The earliest Islamic uses include 'Khaleefa(ḥ)' in The Qur'an, 2:30, where God commands the angels to bow down to Adam) with reverence. "Vicegerent", therefore, is more at "divinely-guided spokesman" than "deputy" in this context and leads to the discovery of the role of Imam in Islam, from the Shi'i or Shi'a point of view where, it is claimed, the spiritual Khilaafat or designation of Khaleefa in this meaning of spiritual and temporal guide falls upon the first Imam, 'Ali ibn Abi Talib, (who received his mission from his cousin Muhammed and who also conceded the Khilaafat to the election and claim of the politically more powerful and more popular leader and his senior, Abu Bakr). In the Shi'i tradition, the dissolved claim to the Khilaafat by Shi'i thereafter crystallised into Imamat which continued with his descendants after him through appointment by nass, or designation.