The mitre (; Greek: μίτρα, "headband" or "turban"), also spelled miter (see spelling differences), is a type of headgear now known as the traditional, ceremonial head-dress of bishops and certain abbots in traditional Christianity; continuing the priestly practice of Temple Judaism. Mitres are worn in the Orthodox Church, Roman Catholic Church, as well as in the Anglican Communion, some  Lutheran churches, and also bishops and certain other clergy in the Eastern Catholic Churches and the Oriental Orthodox Churches. The Metropolitan of the Malankara Mar Thoma Syrian Church also wears a mitre during important ceremonies such as the Episcopal Consecration.

The MITRE Corporation (stylized as MITRE) is an American not-for-profit organization based in Bedford, Massachusetts, and McLean, Virginia. It manages Federally Funded Research and Development Centers (FFRDCs) supporting the Department of Defense (DOD), the Federal Aviation Administration (FAA), the Internal Revenue Service (IRS), the Department of Veterans Affairs (VA), the Department of Homeland Security (DHS), the Administrative Office of the U.S. Courts on behalf of the Federal Judiciary, the Centers for Medicare and Medicaid Services (CMS), and the National Institute of Standards and Technology (NIST).