Thomas Mostyn may refer to:
Sir Thomas Mostyn, 2nd Baronet (1651–1692), one of the Mostyn baronets Thomas Mostyn (sea captain) (fl. 1695–1697), sea captain and slave trader Sir Thomas Mostyn, 4th Baronet (1704–1758), British landowner and politician Sir Thomas Mostyn, 6th Baronet (1776–1831), Welsh politician Thomas Lloyd-Mostyn (1830–1861), British politician