U
- St. Ubaldus
- St. Ulrich
- St. Ulrich of Zell
- St. Ultan of Ardbraccan
- St. Ursula and the Eleven Thousand Virgins
- St. Ursus
- The United States of America
- The United States of America, Statistics
- The University of Aberdeen
- The University of Bologna
- The University of Cracow
- The University of Turin
- The Ursulines
- The Ursulines of Quebec
- Ubaldo Giraldi
- Ubanghi
- Ubanghi-Chari
- Uberaba
- Ubertino of Casale
- Ubiquitarians
- Ucayali
- Uccello
- Udine
- Ugento
- Ugolino Brunforte
- Uhtred
- Ulfilas
- Ulick Joseph Bourke
- Ulissi Aldrovandi
- Ulric Zasius
- Ulrich Ensingen
- Ulrich of Bamberg
- Ulrich of Richenthal
- Ulrich Zell
- Ulrich Zwingli
- Ultramontanism
- Unam Sanctam
- Ungava
- Uniformity Acts
- Unigenitus
- Union of Brest
- Union of Christendom
- Unions of Prayer
- Unitarians
- Unity (As a Mark of the Church)
- Universalists
- Universals
- Universe
- Universities
- University College, Dublin
- University of Alcala
- University of Angers
- University of Avignon
- University of Barcelona
- University of Bonn
- University of Bordeaux
- University of Caen
- University of Cambridge
- University of Coimbra
- University of Cologne
- University of Copenhagen
- University of Dillingen
- University of Fribourg
- University of Granada
- University of Graz
- University of Greifswald
- University of Heidelberg
- University of Ingolstadt
- University of Innsbruck
- University of Leipzig
- University of Louvain
- University of Muenster
- University of Notre Dame
- University of Ottawa
- University of Oxford
- University of Padua
- University of Palermo
- University of Paris
- University of Pavia
- University of Perpignan
- University of Perugia
- University of Pisa
- University of Prague
- University of Rome
- University of Rostock
- University of Saint Andrews
- University of Saint Louis
- University of Saint Mark
- University of Saint Thomas
- University of Salamanca
- University of Santiago
- University of Saragossa
- University of Seville
- University of Siena
- University of St. Francis Xavier's College
- University of St. Joseph's College (Canada)
- University of Tübingen
- University of Upsala
- University of Valence
- University of Valencia
- University of Valladolid
- University of Vienna
- University of Wurzburg
- Unjust Aggressor
- Unyanyembe
- Upper and Lower Nigeria
- Upper Kassai
- Upper Nile
- Upper Rhine
- Upsala
- Uranopolis
- Urbain-Jean-Joseph le Verrier
- Urbi Et Orbi
- Urbino
- Urbs Beata Jerusalem Dicta Pacis Visio
- Urgel
- Urim and Thummim
- Urmiah
- Ursperger Chronicle
- Urubamba
- Uruguay
- Uruguayana
- Use and Abuse of Amulets
- Use of Beads at Prayers
- Use of Numbers in the Church
- Use of Wealth
- Use of York
- Ushaw College
- Usilla
- Usury
- Ut Queant Laxis Resonare Fibris
- Utah
- Uthina
- Utica
- Utilitarianism
- Utopia
- Utraquism
- Utrecht