Khadija (Arabic: خديجه ) was the first wife of the Prophet Muhammad and the first female convert to Islam, the new religion he had begun to preach. She was approximately 15 years his senior when she proposed the idea of marriage. She supported him throughout his mission and such was his love for her that he took no other wife until after her death. The year of her death has been named the "Year of Grief", because of the devastation it caused the Prophet. She was his only wife for about 25 years until her death.

Khadija had five children, one son and four daughters. All five children were born before Muhammad started preaching about Islam. The son, named Qasim, died when he was two. Muhammad was nicknamed Abu Qasim, meaning the father of Qasim. Some Muslim historians argue that some of her daughters were from her previous marriage, while others insist that all her children were by Muhammad.

Her oldest daughter Zainab accepted Islam before her husband and migrated from Mecca to Medina. She died around 8 A.H (A.H means After Hijra). Her other two daughters, Ruqayya and Umm Khulthum, were married to two sons of Muhammad's uncle and a bitter enemy, Abu Lahab who is condemned in chapter 111 of the Qur'an. Both daughters were divorced in retaliation after Muhammad started preaching about Islam. Ruqayya married Uthman ibn Affan, who later became the third caliph, and migrated with him to the city of Axum in Ethiopia when Muslims were being persecuted in Mecca. She later returned to Medina and died around 2 A.H. Uthman then married her sister Umm Khulthum, who died around 9 A.H, without children. Her fourth daughter Fatima was married to Ali ibn Abi Talib, later the fourth Caliph.

Khadija's distant cousin, Waraqah ibn Nawfal, was a monk and a convert to Nestorian Christian sect. When Muhammad reportedly started receiving revelation, Waraqah identified him as the Prophet.