Umar, also spelled Omar (Arabic: عمر بن الخطاب, translit.: `Umar ibn Al-Khattāb, Umar Son of Al-Khattab, born 579 CE – died 3 November 644 CE), was one of the most powerful and influential Muslim caliphs (guardians) in history.
He was a ṣaḥābī or companion of the Islamic prophet Muhammad. He succeeded Abu Bakr (632–634) as the second Rashid of the Rashidun Caliphate on 23 August 634. He was an expert Islamic jurist and is best known for his pious and just nature, which earned him the title Al-Faruq ("the one who distinguishes between right and wrong").
He is sometimes referred to as Umar I by historians of Islam, since a later Umayyad caliph, Umar II, also bore that name.