William X may refer to:
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William X of Aquitaine
William X (Occitan: ''Guillém X''; 1099 – 9 April 1137), called the Saint, was Duke of Aquitaine, Duke of Gascony, and Count of Poitou (as William VIII) from 1126 to 1137.
Early life
William was the son of William IX by his second wife, P ...
(1099–1137)
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Guglielmo X Gonzaga, Duke of Mantua
Guglielmo Gonzaga (24 April 1538 – 14 August 1587) was Duke of Mantua from 1550 to 1587, and of Montferrat from 1574 to 1587. He was the second son of Federico II Gonzaga, Duke of Mantua and Margaret Palaeologina of Montferrat. In 1574, Montferr ...
(1538–1587)
{{hndis, William X