Bertrand I of L'Isle-Jourdain

Bertrand I (died c. 1349) was the first Count of L'Isle-Jourdain in Gascony. In 1340 Philip VI of France raised his lordship to a county, and in 1344 named him the king's lieutenant and commander-in-chief in Guyenne.

He was captured at the Battle of Auberoche on 21 October 1345 by the Earl of Derby's Anglo-Gascon force. He married Isabelle de Lévis in 1328, was last attested on 26 June 1348, and was succeeded by his son Jean Jourdain I.