Guillaume may refer to:
- William the Conqueror (c. 1028-1087), in French Guillaume le Conquérant, Norman conqueror of England
- William of Gellone (755-812/14), in French Guillaume d'Orange, Count of Toulouse and hero of the epic poem Chanson de Guillaume
- Guillaume IV, Grand Duke of Luxembourg
- Prince Guillaume of Luxembourg
- Guillaume, Hereditary Grand Duke of Luxembourg (born 1981), heir apparent to the crown of Luxembourg
|This disambiguation page lists articles associated with the title Guillaume.
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