Sergius III may refer to:
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Pope Sergius III
Pope Sergius III (c. 860 − 14 April 911) was the bishop of Rome and nominal ruler of the Papal States from 29 January 904 to his death. He was pope during a period of violence and disorder in central Italy, when warring aristocratic factions ...
(reigned 897 and 911), Italian-born pope
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Sergius III of Naples
Sergius III was a duke of Naples. He was preceded by his father, Marinus II
Pope Marinus II (died May 946) was the bishop of Rome and ruler of the Papal States from 30 October 942 to his death. He has also been mistakenly called Martinus III ...
, duke in the 990s
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Sergius III of Amalfi, duke in 1031–1073
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