Knight of Stanton Harcourt, Oxfordshire, of Market Bosworth and Ellenhall, Staffordshire, of Wormleighton, Warwickshire. Knight of the Shire ofr Oxfordshire.

Second son of Sir William de Harcourt and Joan de Grey, grandson of Sir John de Harcourt and Eleanor la Zouche, Sir Richard de Grey and Joan FitzPayne.

Thomas married Maud Grey, the daughter of Sir John de Grey of Rotherfield and Avice Marmion, daughter of Sir John. They were married before 13 June 1374 and had three sons and four daughters; John, Sir Thomas, Richard, Anne wife of Thomas Erdington, Katherine, Isabel and probably Maud, wife of Walter de Cokesey and Sir John Philip.

Sir Thomas was heir to is older brother, Sir Richard, by which he inherited most of the Harcourt family estates. Sir Thomas left a will requesting burial at Ronton Priory.