Arnaud-Guilhem de Béarn

Arnaud-Guilhem de Béarn (c. 1330–c. 1391) was the illegitimate son of Gaston II, Count of Foix. Born shortly before his half-brother Gaston III Fébus, he became Fébus's closest collaborator, and by 1353 he was lieutenant-general of Béarn, left with wide powers whenever the count was away.

Through Fébus's reign he led the armies and directed the fortifications. In 1362 Fébus charged him with repudiating Agnes of Navarre, just after she had borne the heir.

He married the heiress of Morlanne, and the Château de Morlanne was built there to complete Fébus's defensive system. He died around 1390, shortly before Fébus.