The Church of Hosios David (Greek: Όσιος Δαβίδ) is a late 5th-century church in Thessaloniki, Greece. In Byzantine times, it functioned as the katholikon of the Latomos Monastery (Greek: Μονή Λατόμου/Λατόμων), and received a rich mosaic and fresco decoration, which was renewed in the 12th–14th centuries. The surviving examples are of high artistic quality. Under Ottoman rule, the building was converted into a mosque (probably in the 16th century), until it was reconsecrated as a Greek Orthodox church in 1921, receiving its present name. In 1988, included among the Paleochristian and Byzantine monuments of Thessaloniki on the list of World Heritage Sites by UNESCO.