Gaillard Thomas Lapsley (1871–1949) was an American constitutional historian and fellow of Trinity College, Cambridge University, 1904-1949.
A brass plaque exists to Lapsley's memory in Trinity College Chapel.
The county palatine of Durham: A study in constitutional history. Longmans Green, New York, 1900.The America of today, being lectures delivered at the local lectures summer meeting of the University of Cambridge, 1918. University Press, Cambridge, 1919."The Parliamentary title of Henry IV", English Historical Review, XLIX (1934).Some recent advance in English constitutional history: (before 1485). University Press, Cambridge, 1936.Crown, community, and Parliament in the later Middle Ages; studies in English constitutional history. Blackwell, Oxford, 1951. (Oxford Studies in Mediaeval History, Vol. 6.)