Namesakes
William Firmatus
(a.k.a. Guillaume) (m) 1026-1103 
Saints
William Breteuil
(a.k.a. Guillaume) (m) ?-1130
Saints
William of Bourges
(a.k.a. Guillaume) (m) 1149-1209
Saints
William of Maleval
(a.k.a. Guillaume) (m) ?-1157
Saints
William Pinchon
(a.k.a. Guillaume) (m) 1175-1234
Saints
William of Pontoise
(a.k.a. Guillaume) (m) ?-1192
Saints
William Tempier
(a.k.a. Guillaume) (m) ?-1197
Saints
William Arnaud
(a.k.a. Guillaume) (m) ?-1242
Saints
Guillaume of Toulouse
(m) 1297-1369
Saints
Guillaume de Machaut
(m) c. 1300-1377
Notable Musicians
Notable Writers
Guillaume Saultemouche
(m) 1555-1593
Saints
Guillaume Répin
(m) 1709-1794
Saints
Guillaume-Joseph Chaminade
(m) 1761-1850
Saints
François Guizot
(a.k.a. Guillaume) (m) 1787-1874
French Presidents and Prime Ministers 1847-1848 (prime minister)
Charles Cousin-Montauban, Comte de Palikao
(a.k.a. Guillaume) (m) 1796-1878
French Presidents and Prime Ministers 1870 (prime minister)
Fabre Geffrard
(a.k.a. Guillaume) (m) 1806-1878
Haitian Presidents 1859-1867 (president)
Vilbrun Guillaume Sam
(m) 1859-1915
Haitian Presidents 1915 (president)
Guillaume Apollinaire
(m) 1880-1918
Notable Writers
Paul van Zeeland
(a.k.a. Guillaume) (m) 1893-1973
Belgian Prime Ministers 1935-1937
Jean, Grand Duke of Luxembourg
(a.k.a. Guillaume) (m) 1921-2019
Other Royalty 1964-2000 Luxembourg (grand duke)
Jan Marijnissen
(a.k.a. Guillaume) (m) 1952-
Notable Politicians and Statespeople
Henri, Grand Duke of Luxembourg
(a.k.a. Guillaume) (m) 1955-
Other Royalty 2000- Luxembourg (grand duke)
Guillaume LeBlanc
(m) 1962-
Olympic Medalists 1992 20 km walk (silver)
Guillaume Canet
(m) 1973-
Notable Actors and Entertainers (actor)
Guillaume Gille
(m) 1976-
Notable Athletes (handball)
Olympic Medalists 2008; 2012 handball (gold)
Guillaume Joli
(m) 1985-
Notable Athletes (handball)
Olympic Medalists 2012 handball (gold)
Jean-Guillaume Béatrix
(m) 1988-
Olympic Medalists 2014 biathlon (bronze)
Emmanuel of Belgium
(a.k.a. Guillaume) (m) 2005-
Other Royalty 2005- Belgium (prince)