The Gillmans are said to have come from the province of Maine, in France, into England with William the Conqueror, and to have settled in Essex, England. Whether a Gaulman, a Gael, or Brookman, from gill, a brook, the same as kill in Dutch, is uncertain.

Arthur, William (1857) An Etymological Dictionary of Family and Christian Names. New York: Sheldon, Blakeman. Public Domain.

GILLMAN. Probably derived from Gill, in its topographical meaning, like Mihnan from Mill, and Hillman from Hill. The Irish family (originally from England in IG'JO) have a tradition of their descent from a Crusader who cut off the right leg of a Saracen — an event supposed to he commemorated in the family arms. B.L.G.

Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.