Mamre (; Hebrew: מַמְרֵא), full name "Oaks of Mamre", refers to an ancient religious site originally focused on a single holy tree growing "since time immemorial" at Hebron in Canaan. At its first location, Khirbet Nimra, a tree cult predated the biblical narrative. It is best known from the biblical story of Abraham and the three visitors. The tree under which he had pitched his tent is known as the oak or terebinth of Mamre. Modern scholars have identified three sites near Hebron which, in different historical periods, have been successively known as Mamre: Khirbet Nimra (a little excavated Persian and Hellenistic period site), Ramat el-Khalil (the best known site, flourished from the Herodian through the Byzantine period), and Khirbet es-Sibte. The last one contained an old oak tree identified by a relatively new tradition as the Oak of Mamre, which collapsed in 2019, and is on the grounds of the Church of the Holy Forefathers and Monastery of the Holy Trinity.

Jewish-Roman historian Josephus, as well as Christian and Jewish sources from the Byzantine period, locate Mamre at the site later renamed in Arabic as Ramat el-Khalil, 4 km north of historical Hebron and approximately halfway between that city and Halhul. Herod the Great initiated the Jewish identification of the site with Mamre, by erecting there a monumental enclosure. It was one of the three most important fairs or marketplaces in Judea, where the fair was held next to the venerated tree accompanied by an interdenominational festival celebrated by Jews, pagans, and Christians alike. This prompted Emperor Constantine the Great to unsuccessfully stop this practice by erecting a Christian basilica there.