Abū al-Qāsim Khalaf ibn al-'Abbās al-Zahrāwī al-Ansari (c. 936–1013), popularly known as al-Zahrawi, Latinised as Albucasis or Abulcasis (from Arabic Abū al-Qāsim), was an Arab physician, surgeon and chemist from al-Andalus. He is considered one of the greatest surgeons of the Middle Ages.

Al-Zahrawi's principal work is the Kitab al-Tasrif, a thirty-volume encyclopedia of medical practices. The surgery chapter of this work was later translated into Latin, attaining popularity and becoming the standard textbook in Europe for the next five hundred years. Al-Zahrawi's pioneering contributions to the field of surgical procedures and instruments had an enormous impact in the East and West well into the modern period, where some of his discoveries are still applied in medicine to this day. He pioneered the use of catgut for internal stitches, and his surgical instruments are still used today to treat people.

He was the first physician to identify the hereditary nature of haemophilia and describe an abdominal pregnancy, a subtype of ectopic pregnancy that in those days was a fatal affliction, and was first to discover the root cause of paralysis. He also developed surgical devices for Caesarean sections and cataract surgeries.

Al-Zahrawi was born in the city of Azahara, 8 kilometers northwest of Cordoba, Andalusia. His birth date is not known for sure, however, scholars agree that he was born around 936, the year his birthplace city of Azahara was founded. The nisba (attributive title), Al-Ansari, in his name, suggests origin from the Medinian tribe of Al-Ansar, thus, tracing his ancestry back to Medina in the Arabian Peninsula.

He lived most of his life in Cordoba. It is also where he studied, taught and practiced medicine and surgery until shortly before his death in about 1013, two years after the sacking of Azahara.

Few details remain regarding his life, aside from his published work, due to the destruction of El-Zahra during later Castillian-Andalusian conflicts. His name first appears in the writings of Abu Muhammad bin Hazm (993–1064), who listed him among the greatest physicians of Moorish Spain. But we have the first detailed biography of al-Zahrawī from al-Ḥumaydī's Jadhwat al-Muqtabis (On Andalusian Savants), completed six decades after al-Zahrawi's death.

Al-Zahrawi was a court physician to the Andalusian caliph Al-Hakam II. He was a contemporary or near contemporary of Andalusian chemists such as Ibn al-Wafid, al-Majriti and Artephius. He devoted his entire life and genius to the advancement of medicine as a whole and surgery in particular. As a court physician, Zahrawi had access to the most advanced medical knowledge and resources of the time, allowing him to develop new techniques and instruments for surgical procedures. Zahrawi's time as a court physician to Al-Hakam II allowed him to develop his skills and knowledge as a physician and surgeon, and to make significant contributions to the field of medicine. His work helped to lay the foundation for modern surgical techniques and has had a lasting impact on the practice of medicine.

Al-Zahrawi specialized in curing disease by cauterization. He invented several devices used during surgery, for purposes such as inspection of the interior of the urethra and also inspection, applying and removing foreign bodies from the throat, the ear and other body organs. He was also the first to illustrate the various cannulae and the first to treat a wart with an iron tube and caustic metal as a boring instrument.