Arnaud Odon of Lomagne

Arnaud Odon (died between 1264 and 1267) was Viscount of Lomagne and, by marriage, Count of Armagnac and Fézensac. He wed his cousin Mascarose I, succeeding her brother Bernard V in 1243. A cousin, Géraud of Fézensaguet, denied women could inherit and made war with Toulouse's backing, while Henry III of England backed Arnaud Odon. After Mascarose died in 1246 he ruled the counties as regent for their daughter Mascarose II until she married.

The dispute ended with her childless death in 1254. By his second wife Escarone he fathered Vezian III, later Viscount of Lomagne; a third marriage produced a daughter, Philippa.