Prince Louis Thomas of Savoy (German: Ludwig Thomas von Savoyen, Graf von Soissons; Italian: Luigi Tommaso di Savoia; 15 December 1657 – 14 August 1702) was a Count of Soissons and Prince of Savoy. He was killed as Feldzeugmeister of the Imperial Army at the Siege of Landau at the start of the War of the Spanish Succession. There was speculation that he was an illegitimate child of Louis XIV.

Louis Thomas was the eldest son of Eugene Maurice, Count of Soissons and Olympia Mancini, as well as the oldest brother of Prince Eugene of Savoy. He married Uranie de La Cropte de Beauvais, whom Saint-Simon had once described as "radiant as the glorious morn". His daughter Princess Maria Anna Victoria of Savoy eventually inherited Eugene's estate. His maternal cousins included the Duke of Vendôme as well as the Duke of Bouillon and Louis Henri de La Tour d'Auvergne. His paternal cousins included Victor Amadeus I, Prince of Carignano and Louis William, Margrave of Baden-Baden.

After the death of his father and the flight of his mother to Brussels due to her involvement in the notorious Poison affair, Louis Thomas and Urania were charged, along with his paternal grandmother, with the rearing of his younger brothers. Eugene was never to forget the couple's loving surrogate parentage.

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