William I, Viscount of Béarn

William of Montcada ( Catalan: Guillem de Montcada, French: Guillaume de Moncade, † 1172 ) was jure uxoris a Viscount of Béarn ( William I ) from the Catalan House Montcada. He was the eldest son of the famous Catalan seneschal Guillem Ramon de Montcada II (el Gran Senecal, † 1173 ) and the Beatriu de Montcada.

Wilhelm was first mentioned in a document issued on June 10, 1164 deed as husband of Mary of Béarn, the sister of the Viscount of Béarn Gaston V.. This marriage was apparently still of Count Raymond Berenguer IV of Barcelona ( † 1162 ) were arranged, under whose guardianship the Béarnaise siblings had been. After Gaston V. died in 1170 without children could begin its successor in the vice county Mary and William. 1171 Wilhelm made ​​against King Alfonso II of Aragon fealty for the Béarn. Only a year later, he died before his father.

From his marriage with Mary of Béarn had two sons:

• Gaston VI. († 1214 ), Viscount of Béarn
• Wilhelm Raimund († 1224 ), Lord of Montcada and Vic, Viscount of Béarn