Eustache de Beaumarchais ("c". 1235 – 23 August 1294) was a French baron and military leader who served as seneschal of the County of Poitou (1268–76) and the County of Toulouse (1272–94). He took part in the War of the Navarrería in 1276–77 and in the Aragonese Crusade in 1284–85.