Lucien Rosengart (11 January 1881 in Paris, France – 27 July 1976) was a French engineer.
His early life was shaped by carriages and the advance of the automobile age. He first started working as a mechanic at the age of 12, and by age 24 he had a machine shop in Belleville and several patents to his credit. By 1914 his products included railway parts, bicycle parts, and a rocket that allowed artillery shells to be exploded while airborne. This attracted the attention of the French Government and they set him up with two factories, one in Paris and one in Saint-Brieuc - at this point he began working with Andre Citroën's company, which provided the shells. By the end of the first world war, he'd become a skilled businessman and helped both Peugeot and Citroën stave off bankruptcy. Involvement with these companies led Rosengart to think of building his own car. He was already making bicycles.