Carlos I may refer to:
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Carlos I of Spain (1500–1558), also Charles V of the Holy Roman Empire
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Carlos I of Portugal
Dom (title), ''Dom'' Carlos I (; 28 September 1863 – 1 February 1908), known as "the Diplomat" (), "the Oceanographer" () among many other names, was List of Portuguese monarchs, King of Portugal from 1889 until his Lisbon Regicide, assassin ...
(1863–1908), King of Portugal
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Juan Carlos I of Spain
Juan Carlos I (; Juan Carlos Alfonso Víctor María de Borbón y Borbón-Dos Sicilias, born 5 January 1938) is a member of the Spanish royal family who reigned as King of Spain from 22 November 1975 until Abdication of Juan Carlos I, his abdic ...
(born 1938), King of Spain
{{hndis, Carlos 01