Julien du Casse was a French arms dealer, a Templar, and a minor character in Assassin's Creed IV: Black Flag. Born in France, du Casse joined his uncle on the seas at a young age, fighting in the War of Spanish Succession. In 1704, du Casse deserted from the French Army and traveled to the West Indies. Taking any dirty job he could to make large sums of money, du Casse eventually met Governor Laureano de Torres y Ayala and joined the Templars.
In 1715, du Casse, along with Woodes Rogers and Torres, met Edward Kenway in disguise as Duncan Walpole. After the meeting, du Casse was appointed captain of the El Arca del Maestro and began smuggling weapons, gold and supplies for the Templars.