Thomas de Clare, Lord of Inchiquin and Youghal (c. 1245 – 29 August 1287) was a Hiberno-Norman peer and soldier. He was the second son of Richard de Clare, 6th Earl of Gloucester and his wife Maud de Lacy, Countess of Gloucester. On 26 January 1276 he was granted the lordship of Thomond by Edward I of England; he spent the next eight years attempting to conquer it from the O'Brien dynasty, kings of Thomond.