Thomas Francis of Savoy, Prince of Carignano (Italian: Tommaso Francesco di Savoia, Principe di Carignano, French: Thomas François de Savoie, Prince de Carignan; 21 December 1596 – 22 January 1656) was an Italian military commander and the founder of the Savoy-Carignano branch of the House of Savoy, which reigned as kings of Sardinia from 1831 to 1861, and as kings of Italy from 1861 until the dynasty's deposition in 1946.

Born in Turin, Thomas was the youngest of the five legitimate sons of the sovereign Duke Charles Emmanuel I, Duke of Savoy by his consort Catherine Micaela of Spain, a daughter of King Philip II of Spain and the French princess Elizabeth of Valois. His mother died the following year. While still a young man, Thomas bore arms in the service of the king of Spain in Italy.

Although in previous reigns, younger sons had been granted rich appanages in Switzerland (Genevois, Vaud), Italy (Aosta), or France (Nemours, Bresse), the Savoy dukes found that this inhibited their own aggrandizement while encouraging intra-dynastic strife and regional secession. Not only did Thomas have older brothers, he was but one of the twenty-one acknowledged children of Charles Emmanuel. While only nine of these were legitimate, the others, being the widowed duke's offspring by noble mistresses, appear to have been generously endowed or dowered during their father's lifetime.

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