Gaston Fébus [or Phoebus] (30 April 1331 – 1391) was the eleventh count of Foix (as Gaston III) and viscount of Béarn (as Gaston X) from 1343 until his death.
Gaston was born either in Orthez or Foix, the son of Gaston II/IX (1308–1343). His native language was Gascon (a dialect of Occitan), but he was also fluent in French. He wrote a treatise on hunting in French, and an Occitan song, Se Canta, has been ascribed to him. One contemporary records that he "very willingly spoke to me not in his native Gascon but in proper and elegant French".
Béarn had passed to the county of Foix in 1290. Gaston paid homage to the French king for his own county, but starting in 1347 he refused to give homage for Béarn, which he claimed as an independent fief, with its chief seat his stronghold at Pau, a site that had been fortified by the 11th century, which was later made the official capital of Béarn in 1464.
He was succeeded as count of Foix by Mathieu of Foix-Castelbon.
The house of Béarn-Foix was engaged in a long running feud with the family of D'Armagnac. In 1362, a battle was fought between the two sides at Launac. Gaston Fébus was victorious and succeeded in capturing his chief rivals, whom he ransomed for a vast fortune of at least 600,000 florins. This money was stored in the Moncade tower in Orthez, where Fébus also created a gallery of portraits and military trophies to commemorate the event.
In the 1380s, Jean Froissart visited the County of Foix. He recorded the splendor of the court of Orthez under Gaston Fébus in the latter half of the 14th century. Gaston recorded the three "special delights" of his life as "arms, love and hunting"; he wrote an important treatise on the latter entitled Livre de chasse.