1. See also

Guillaume IV may refer to:

• William IV, Duke of Aquitaine (937–994)
• William IV, Count of Nevers (c. 1130–1168)
• William IV, Grand Duke of Luxembourg (1852–1912)

See also

• William IV (disambiguation)

• Piculus leucolaemus
• Piculus litae
• Piculus rivolii
• Piculus simplex
• Picumnus albosquamatus
• Picumnus aurifrons
• Picumnus (bird)
• Picumnus castelnau
• Picumnus cinnamomeus
• Picumnus cirratus
• Picumnus dorbignyanus
• Picumnus dorbygnianus
• Picumnus exilis
• Picumnus fulvescens
• Picumnus fuscus
• Picumnus granadensis
• Picumnus innominatus
• Picumnus lafresnayi
• Picumnus limae
• Picumnus minutissimus
• Picumnus nebulosus
• Picumnus nigropunctatus
• Picumnus olivaceus
• Picumnus pumilus
• Picumnus pygmaeus