Belgian Prime Ministers: 1 prime minister
Paul van Zeeland (a.k.a. Guillaume)   1935-1937  
French Presidents and Prime Ministers: 2 prime ministers
(prime minister) François Guizot (a.k.a. Guillaume)   1847-1848  
(prime minister) Charles Cousin-Montauban, Comte de Palikao (a.k.a. Guillaume)   1870  
Haitian Presidents: 2 presidents
(president) Fabre Geffrard (a.k.a. Guillaume)   1859-1867  
(president) Vilbrun Guillaume Sam   1915  
Notable Actors and Actresses: 1 actor
Guillaume Canet   1973-  
Notable Athletes: 2 handball
(handball) Guillaume Gille   1976-  
(handball) Guillaume Joli   1985-  
Notable Musicians: 1 composer
Guillaume de Machaut   c. 1300-1377     
Notable Politicians and Statespeople: 1 politician
Jan Marijnissen (a.k.a. Guillaume)   1952-  
Olympic Medalists: 2 gold, 1 bronze, 1 silver
(silver) Guillaume LeBlanc   1992   20 km walk  
(gold) Guillaume Gille   2008; 2012   handball  
(gold) Guillaume Joli   2012   handball  
(bronze) Jean-Guillaume Béatrix   2014   biathlon  
Other Royalty: 2 grand dukes, 1 prince
Jean, Grand Duke of Luxembourg (a.k.a. Guillaume)   1964-2000   Luxembourg  
Henri, Grand Duke of Luxembourg (a.k.a. Guillaume)   2000-   Luxembourg  
Emmanuel of Belgium (a.k.a. Guillaume)   2005-   Belgium  
Saints: 7 blessed, 5 saints
Saint William Firmatus (a.k.a. Guillaume)   1026-1103  
Saint William Breteuil (a.k.a. Guillaume)   ?-1130  
Saint William of Bourges (a.k.a. Guillaume)   1149-1209  
Blessed William of Maleval (a.k.a. Guillaume)   ?-1157  
Saint William Pinchon (a.k.a. Guillaume)   1175-1234  
Saint William of Pontoise (a.k.a. Guillaume)   ?-1192  
Blessed William Tempier (a.k.a. Guillaume)   ?-1197  
Blessed William Arnaud (a.k.a. Guillaume)   ?-1242  
Blessed Guillaume of Toulouse   1297-1369  
Blessed Guillaume Saultemouche   1555-1593  
Blessed Guillaume-Joseph Chaminade   1761-1850  
Blessed Guillaume Répin   1793-1794