Deir al-Balah (Arabic: دير البلح, lit. 'Monastery of the Date Palm') is a city in the center of the Gaza Strip, Palestine, and the administrative capital of the Deir al-Balah Governorate. It is located over 14 kilometers (8.7 mi) south of Gaza City. The city had a population of 75,132 in 2017. The city is known for its date palms, after which it is named.

Deir al-Balah dates back to the Late Bronze Age when it served as a fortified outpost for the New Kingdom of Egypt. A monastery was built there by the Christian monk Hilarion in the mid-4th century AD and is currently believed to be the site of a mosque dedicated to Saint George, known locally as al-Khidr. During the Crusader-Ayyubid wars, Deir al-Balah was the site of a strategic coastal fortress known as "Darum" which was continuously contested, dismantled and rebuilt by both sides until its final demolition in 1196. Afterward, the site grew to become a large village on the postal route of the Mamluk Sultanate (13th–15th centuries). It served as an episcopal see of the Greek Orthodox Church of Jerusalem during Ottoman times until the late 19th century.

Egyptian occupation after 1948 saw the population triple from the influx of refugees during the 1948 Arab–Israeli War. It was a prosperous agricultural town. Israel captured the region during the Six-Day War. Deir al-Balah became the first city to come under Palestinian self-rule in 1994. Since the outbreak of the Second Intifada in 2000, it has witnessed frequent incursions by the Israel Defense Forces with the stated aim of stopping Qassam rocket fire into Israel. Ahmad Kurd, a Hamas member, was elected mayor in late January 2005.

By late 2024, a tented camp had been established at Deir al-Balah. "Smile of Hope Camp" is managed by the Palestinian Red Crescent and provides care and facilities for people with disabilities.

"Deir al-Balah", which in Arabic translates as the "Monastery of the Date Palm", was named after the grove of date palms that lay west of the city. Its name dates back to the late 19th century, before which the city was locally known as "Deir Mar Jiryis" or "Deir al-Khidr" and "Deir Darum" in Ottoman records. "Mar Jiryis" translates as "Saint George" while in Islamic tradition al-Khidr could either refer to Saint George or Elijah. The inhabitants of Deir al-Balah associated al-Khidr with Saint George. The town had been named after al-Khidr, the most venerated saintly person throughout Palestine. The mosque in Deir al-Balah which bears his name is traditionally believed by locals to contain his tomb.

Up until the later Ottoman era, Deir al-Balah was referred to in Arabic as "Darum" or "Darun" which derived from the settlement's Crusader-era Latin name "Darom" or "Doron." That name was explained by the Crusader chronicler William of Tyre as a corruption of domus Graecorum, "house of the Greeks" (dar ar-rum). More recently, the eighteenth century scholar Albert Schultens supposed its roots are the Ancient Hebrew name "Darom" or "Droma", from the Hebrew root for "south", which referred to the area south of Lydda, i.e. the southern parts of the coastal plain and Judean foothills together with the northern Negev Desert. During early Arab rule, "ad-Darum" or "ad-Dairan" was the name of the southern subdistrict of Bayt Jibrin, a corruption of the Aramaic name of the region, Daroma.

Deir al-Balah is situated in the central Gaza Strip, along the coastline of the eastern Mediterranean Sea. Its city center is about 1,700 meters (5,600 ft) east of the coast while the ancient site of Darum was uncovered 3 kilometers (1.9 mi) to the south of central Deir al-Balah. While the city's municipal borders stretch eastward toward the border with Israel, its urban area does not extend beyond the main Salah al-Din Highway to the east.

Nearby localities include Nuseirat Camp and Bureij Camp to the north, Maghazi Camp to the northeast and Wadi as-Salqa to the south. Khan Yunis is 9.7 kilometers (6.0 mi) to Deir al-Balah's south and Gaza City is located 14.6 kilometers (9.1 mi) to the north.