Mohammed Deif

Mohammed Deif محمد الضيف
Birth name	Mohammed Diab Ibrahim al-Masri
Nickname(s)	Abu Khaled (kunya) The mastermind (Palestinian nickname) The cat with nine lives (Israeli nickname)
Born	1965 (age 58–59) Khan Yunis refugee camp, Gaza Strip (under Egyptian rule)
Allegiance	Hamas (Izz ad-Din al-Qassam Brigades)
Years of service	1987–present
Rank	Chief of Staff (2002–present)
Battles/wars	First Intifada Second Intifada Gaza–Israel conflict 2012 Gaza War 2014 Gaza War 2021 Israel–Palestine crisis 2023 Israel–Hamas war 2023 Hamas attack on Israel 2023 Israeli invasion of the Gaza Strip
Alma mater	Islamic University of Gaza
Spouse(s)	Widad Asfoura ​ ​ (m. 2007; died 2014)​ (killed by an Israeli airstrike)
Children	4 (2 deceased, killed by an Israeli airstrike)

Mohammed Deif (Arabic: محمد الضيف), born Mohammed al-Masri (Arabic: محمد المصري), is a Palestinian militant and the head of the Izz ad-Din al-Qassam Brigades, the military wing of the Islamist organization Hamas.

Mohammed al-Masri was born in 1965 in the Khan Yunis Refugee Camp in the Gaza Strip that was set up after the 1948 Palestine war. He reportedly left school temporarily to support his low-income family. He graduated with a bachelor's degree in chemistry from the Islamic University of Gaza in 1988.

Masri joined Hamas in 1987 and became known as Mohammed Deif, meaning 'guest' in Arabic, possibly in reference to the nomadic lifestyle he adopted to avoid being targeted. During the 1990s and early 2000s, he planned several suicide bombing attacks, including the 1996 Jaffa Road bus bombings. He became the head of the al-Qassam Brigades in 2002, and has since developed the group's capabilities, transforming it from a cluster of amateur cells to organized military units. He has masterminded the group's strategy of combining rocket attacks on Israel with tunnel warfare, and was central to planning the 2023 Hamas-led attack on Israel that initiated the 2023 Israel–Hamas war.

Deif has been the Israeli military's 'most wanted' man since 1995 for killing Israeli soldiers and civilians. He was detained by the Palestinian Authority at Israel's request in 2000 before escaping months later. He has survived at least seven Israeli assassination attempts since 2001, the most recent of which came during the 2021 Israel–Palestine crisis. His wife, infant son, and 3-year-old daughter were killed in an Israeli airstrike in 2014. The United States Department of State added Deif to its list of Specially Designated Global Terrorists in 2015. The European Union added Deif to their terrorist blacklist in 2023.