The following monarchs either lost their thrones through deposition by a coup d'état, by a referendum which abolished their throne, or chose to abdicate during the 20th century. A list of surviving former monarchs appears at the end of the article.
See also: Abolished monarchy, List of current monarchs, List of non-sovereign monarchs who found their thrones in the 20th century
A
Australia
King Edward VIII abdicated in 1936 in favour of his brother George VI.
Afghanistan
King Amānullāh Khān ceased to be Emir of Afghanistan in 1926, abdicated in 1929. King Inayatullah Khan abdicated in 1929. King Habibullāh Kalakāni was overthrown in 1929. King Mohammed Nadir Shah was assassinated in 1933 while attending graduation day. King Mohammed Zahir Shah was deposed in a coup in 1973.
Albania (Principality) Prince William fled Albania in 1914 following the outbreak of World War I (he was formally deposed in 1925).
Albania (Kingdom) King Zog I (president turned monarch) was deposed by Italy under Benito Mussolini in 1939. King Victor Emmanuel III of Italy, also King of Albania abdicated in 1943 after the Italian capitulation. Regent Mehdi Frashëri was deposed in 1944 when the National Liberation Movement took over Albania.
Austria-Hungary
Emperor-King Charles I & IV was deposed in 1918, also he was deposed as a non-sovereign monarch in several lands in Austria and Hungary.
B
Baluchistan
Mir Ahmad of Kalat was the last ruler of the Khanate of Kalat in Baluchistan. On 27 March 1948 he acceded to Pakistan.
Belgium
King Leopold III was forced to abdicate in 1951 in favour of his son, King Baudouin.
Brunei
Omar Ali Saifuddien III, Sultan of Brunei, abdicated voluntarily in 1967 in favour of his son Hassanal Bolkiah.
Bulgaria
Tsar Ferdinand I abdicated in 1918 in favour of his son Tsar Boris III, following World War I. Tsar Simeon II never abdicated but was exiled by the Bulgarian government following a national referendum in 1946 after which Bulgaria became a People's Republic. After the fall of communism in Bulgaria, he returned to the country in 1996, and was elected as Prime Minister in 2001, serving until 2005. He and Norodom Sihanouk of Cambodia are the only monarchs in recent history to become democratically elected heads of government.
Burundi
King Mwambutsa IV was deposed by his son Ntare V in 1966. King Ntare V was deposed in 1966 in a military coup led by Michel Micombero.
C
Cambodia
King Norodom Sihanouk abdicated in 1955, then served in various important positions, including prime minister and head of state, intermittently until 1976, and was eventually restored to the kingship in 1993. He abdicated a second time in favour of his son, Norodom Sihamoni, on 7 October 2004. Queen Sisowath Kossamak was deposed in 1970 with the coup that ended the regime of Prince Norodom Sihanouk. The monarchy was restored in 1993 with Sihanouk (who had previously reigned from 1941 to 1955) as King.
Canada
King Edward VIII abdicated in 1936 in favour of his brother George VI.
Central African Empire
Bokassa I (president turned monarch), Emperor of Central African Empire, deposed in 1979.
Ceylon
Elizabeth II ceased to be Queen of the Dominion of Ceylon in 1972 when the country became a republic called Sri Lanka.
China
Xuantong Emperor (Puyi) was forced to abdicate in 1912 following a Republican revolution. Yuan Shikai (reigned as the self-proclaimed Hongxian Emperor) abdicated in 1916, a few months before his death, and lasting only 83 days on the throne. Xuantong Emperor (Puyi) briefly regained power but, was forced to abdicate again in 1917 following another Republican revolution.
Croatia
Designated King Tomislav II (Prince Aimone, Duke of Spoleto) of the Independent State of Croatia abdicated in 1943 after the Italian capitulation.
D
Denmark
King Christian X was deposed by Adolf Hitler in 1940, returned 1946.
E
Egypt
King Fuad I Died in 1936 in favor of his son Farouk. King Farouk abdicated in 1952 in favor of his infant son Fuad II. King Fuad II was deposed in 1953.