Thomas St Lawrence, 13th Baron Howth (1659–1727) was an Irish nobleman of the later Stuart and early Georgian era.
He was born in 1659, eldest son of William St Lawrence, 12th Baron Howth, and Elizabeth Fitzwilliam.
At first, he supported James II, and sat in the Patriot Parliament of 1689, but after the failure of the Jacobite cause he quickly transferred his loyalty to William III, sitting in the Irish Parliament of 1692, and signing the Declaration of Loyalty to the person and government of the King in 1697.
He was also noted for charity, and left a large sum in his will for the relief of the poor of the parish of Howth.
Elrington Ball[3] quotes an elegy on his death in 1727 which pays tribute to his virtues: "Behold this stone whose vault contains More precious dust than India's veins, For honour's sake then shed a tear, Since honour's self lies buried here."