The marshal was an honourable officer in the royal household, or in the households of the higher nobility. Like most household offices, that of marshal ultimately derives from the Carolingian court; their recorded history in England goes back no further than Domesday Book, though the office itself was almost certainly older than that. The marshal, normally a deputy of the constable in military matters, may derive from the same source, the royal 'horse-thegns' first recorded in the reign of Alfred the Great.
Domesday Book records one Anglo-Saxon marshal, Alfred (CON 5,1,3), and three Normans with that title: Geoffrey in Hampshire and Wiltshire, Gilbert in Oxfordshire, and Robert in Wiltshire. None of these were wealthy landowners; but Ansketel of Rots, one of the 100 wealthiest men in the kingdom, was identified as a marshal in one of the Domesday satellite texts, the Excerpta of St Augustine's, Canterbury.
For further detail, see J.H. Round, 'The officers of Edward the Confessor', English Historical Review, vol. 19 (1904), pages 90-92; L.M. Larson, The king's Household in England before the Norman Conquest (1904); and David Crouch, The image of aristocracy in Britain, 1000-1300 (1992).