Sebastian G. Longchamps (1718 - 1793) was a manservant and map publisher active in the mid to late 18th century. Longchamps is best known for his long-term employment as the Cirey valet of the French polymath François-Marie Arouet (1694 - 1778), a.k.a. 'Voltaire'. Much of what is known about Longchamps (Longchamp) is obscured as little more than an anecdote in the long shadow of Voltaire, but he was substantial in his own right and worthy of academic attention. Lonchamps' writings on Voltaire are the primary source of information on the author's Cirey period. Less known is Longchamps' map publishing career, which he pursued simultaneously with his valet work.