A Brief History of the Marque
Alexandre Darracq built the 5 cylinder Millet motorcycles and tricycles, and the Perfecta tricycles with Soncin or Aster engines.
Darracq and Paul Aucoq were the founders of Compagnie des Cycles Gladiator which built bicycles, autombiles and motorcycles.
By 1904 Darracq & Cie was one of the largest producers of automobiles in France, and in 1906 Darracq founded Società Anonima Italiana Darracq in Milan, the company which became Alfa Romeo.
Sources: Bourdache (pp 21, 33, 49, 105, 261, 274.), Wikipedia.