- Ua Buachalla, Domhnall (Donal Buckley)
- Uganda: Archontology
- Uganda: Gazette 1962-11-02
- Uganda: Governors-General: 1962-1963
- Uganda: Heads of State: 1962-1963
- Uganda: Heads of State: 1963-2024
- Uganda: Polity Style: 1962-2024
- Uganda: Sources
- Ukraine: Archontology
- Ukraine: Chairman of the Central Executive Committee: 1919-1938
- Ukraine: Chairman of the People's Secretariat: 1917-1918
- Ukraine: Chairmen of the Central Executive Committee
- Ukraine: Chairmen of the Central Rada: 1917-1918
- Ukraine: Chairmen of the Council of Ministers: 1946-1991
- Ukraine: Chairmen of the Council of People's Commissars: 1919-1946
- Ukraine: Chairmen of the Presidium of the Supreme Council: 1938-1990
- Ukraine: Chairmen of the Supreme Council: 1990-1991
- Ukraine: Directory: 1918-1920
- Ukraine: Heads of Government: 1917-1918
- Ukraine: Heads of Government: 1918
- Ukraine: Heads of Government: 1918-1920
- Ukraine: Heads of State: 1991-2024
- Ukraine: Heads of the Provisional Government: 1918-1919
- Ukraine: Hetman: 1918
- Ukraine: Polity Style: 1917-1920
- Ukraine: Polity Style: 1917-1991
- Ukraine: Polity Style: 1991-2024
- Ukraine: Prime Minister: 1991
- Ukraine: Sources
- United Arab Emirates: Abu Dhabi: Archontology
- United Arab Emirates: Abu Dhabi: Polity Style: 1761-2024
- United Arab Emirates: Abu Dhabi: Rulers: 1761-2024
- United Arab Emirates: Ajman: Archontology
- United Arab Emirates: Ajman: Heads of State: 1700-2024
- United Arab Emirates: Ajman: Heads of State: 1700-2024
- United Arab Emirates: Ajman: Polity Style: 1700-2024
- United Arab Emirates: Archontology
- United Arab Emirates: Dubai: Archontology
- United Arab Emirates: Dubai: Heads of State: 1800-2024
- United Arab Emirates: Dubai: Polity Style: 1800-2024
- United Arab Emirates: Fujairah: Archontology
- United Arab Emirates: Fujairah: Heads of State: 1900-2024
- United Arab Emirates: Fujairah: Polity Style: 1900-2024
- United Arab Emirates: Glossary
- United Arab Emirates: Heads of State: 1971-2024
- United Arab Emirates: Kalba: Archontology
- United Arab Emirates: Kalba: Heads of State: 1871-1952
- United Arab Emirates: Kalba: Polity Style: 1871-1952
- United Arab Emirates: Polity Style: 1971-2024
- United Arab Emirates: Ras al-Khaimah: Archontology
- United Arab Emirates: Ras al-Khaimah: Polity Style: 1700-2024
- United Arab Emirates: Sharjah: Archontology
- United Arab Emirates: Sharjah: Heads of State: 1800-2024
- United Arab Emirates: Sharjah: Polity Style: 1800-2024
- United Arab Emirates: Umm al-Quwain: Archontology
- United Arab Emirates: Umm al-Quwain: Heads of State: 1775-2024
- United Arab Emirates: Umm al-Quwain: Polity Style: 1775-2024
- United Arab Republic: Archontology
- United Arab Republic: Heads of State: 1958-1961
- United Arab Republic: Polity Style: 1958-1961
- United Indonesia: Archontology
- United Indonesia: Heads of State: 1960-1961
- United Indonesia: Polity Style: 1960-1961
- United Kingdom: Archontology
- United Kingdom: Heads of State: 1801-2024
- United Kingdom: Polity Style: 1707-2024
- United Kingdom: Prime Ministers: 1730-2024
- United Kingdom: Prime Ministers: 1905-2024
- United Kingdom: Principal Ministers: 1730-1905
- United Kingdom: Sources
- United States of Indonesia: Archontology
- United States of Indonesia: Heads of State: 1949-1950
- United States of Indonesia: Polity Style: 1949-1950
- United States: Archontology
- United States: Heads of State: 1789-2024
- United States: Notes
- United States: Polity Style: 1781-2024
- United States: Presidents of Congress: 1774-1789
- United States: Sources
- Upper Canada: Archontology
- Upper Canada: Governors: 1792-1841
- Upper Canada: Polity Style: 1791-1841
- Upper Canada: Sources
- Uruguay: Archontology
- Uruguay: Governors: 1814-1817
- Uruguay: Heads of State: 1825-1830
- Uruguay: Heads of State: 1830-1919
- Uruguay: Heads of State: 1952-2024
- Uruguay: Polity Style: 1814-2024
- Uruguay: Presidents of the National Council of Administration: 1919-1933
- Uruguay: Presidents of the Republic: 1919-1952
- Uruguay: Sources
- USSR: Communist Party Leadership: 1917-1991
- USSR: Communist Party: 1917-1952 (Politburo)
- USSR: Communist Party: 1919-1952 (Orgburo)
- USSR: Communist Party: 1919-1991 (Secretariat)
- USSR: Communist Party: 1922-1991 (Leadership history)
- USSR: Communist Party: 1952-1966 (Presidium)
- USSR: Communist Party: 1966-1991 (Politburo)
- USSR: Communist Party: Congresses
- USSR: Communist Party: Orgburo
- USSR: Communist Party: Politburo
- USSR: Communist Party: Presidium
- USSR: Communist Party: Secretariat
- USSR: Communist Party: transitional period: 1917-1919
- USSR: Party Congresses: 1898-1990
- Uzbekistan: Archontology
- Uzbekistan: Chairman of the Central Executive Committee: 1925-1938
- Uzbekistan: Chairmen of the Presidium of the Supreme Council: 1938-1990
- Uzbekistan: Heads of State: 1991-2024
- Uzbekistan: Polity Style: 1925-1991
- Uzbekistan: Polity Style: 1991-2024
- Uzbekistan: President of the Republic: 1990-1991
- Uzbekistan: Sources
Last update: 04 Oct 2024